Variation of the Molecular Conformation, Shape, and Cavity Size in

Article pubs.acs.org/IC

Variation of the Molecular Conformation, Shape, and Cavity Size in Dinuclear Metalla-Macrocycles Containing Hetero-Ditopic Dithiocarbamate−Carboxylate Ligands from a Homologous Series of N‑Substituted Amino Acids Aaron Torres-Huerta,† Jorge Cruz-Huerta,† Herbert Höpfl,*,† Luis G. Hernández-Vázquez,† Jaime Escalante-García,† Arturo Jiménez-Sánchez,‡ Rosa Santillan,‡ Irán F. Hernández-Ahuactzi,§ and Mario Sánchez∥ †

Centro de Investigaciones Químicas, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Chamilpa, Cuernavaca 62209, Morelos, México ‡ Departamento de Química, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, México 07360, México § Centro Universitario de Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico 555, Ejido San José Tatepozco, Tonalá 48525, Jalisco, México ∥ Centro de Investigación, Advanced Materials Research Center, Alianza Norte 202, PIIT, Carretera Monterrey-Aeropuerto Km. 10, Apodaca 66628, Nuevo Leon, México S Supporting Information *

ABSTRACT: A homologous series of dithiocarbamate ligands derived from N-substituted amino acids was reacted with different diorganotin dichlorides to give 18 diorganotin complexes. Spectroscopic and mass spectrometric analysis evidenced the formation of assemblies with six-coordinate tin atoms embedded in skewed-trapezoidal bipyramidal coordination environments of composition C2SnS2O2. Single-crystal Xray diffraction analysis for three of the compounds revealed a one-dimensional polymeric structure for the complex with the ligand derived from 5-aminopentanoic acid, which through further intermolecular Sn···O interactions generated an overall twodimensional coordination polymer containing 40-membered hexanuclear tin macrocycles. On the contrary, the ligands derived from 6-aminohexanoic and 8-aminooctanoic acid provided the expected 22- and 26-membered dinuclear macrocyclic structures. Density functional theory calculations for a representative series of macrocyclic complexes of composition [Me2SnLx]2 with Lx = ¯S2CN(Me)-(CH2)x-COO¯ (x = 3−12) enabled a detailed analysis of the variations in the molecular conformation, shape, and cavity size of the macrocycles in dependence of the aliphatic spacer. Because of odd−even effects, the difunctional ligands can adopt either a curved or a twisted-pincer shape, while the SnSxO4‑x (x = 0−4) moieties can act either as linear or angular tectons with varying connectivity angles.

1. INTRODUCTION

Amino acids are organic molecules that play an important role in several biological processes. In the presence of metals, amino acids are excellent ligands having two different coordination functions, both of which are commonly employed in coordination chemistry. On the one hand, carboxylate groups have been widely used for the coordination to single and multiple metal centers because of their bidentate coordination chemistry. On the other hand, amino groups coordinate well to transition metals and main-group elements, and can be, additionally, transformed into dithiocarbamates.28,29 Using ligands derived from amino acids, in organotin chemistry so far mainly mononuclear complexes

1,2

In coordination-driven self-assembly, organometallic building blocks are of current interest, since the metal−carbon bond connectivity allows to modify a number of chemically important variables of the metal centers such as the Lewis acidity, oxidation potential, coordination number, and steric bulk, among others.3,4 In this context, organotin-based constructs have become relevant during the past years, and an increasing number of 0D, 1D, 2D, and 3D assemblies is documented in the literature. Of these, the vast majority has been derived from carboxylate and dithiocarbamate-functionalized ligands.5−21 Organotin complexes are of interest further because of their fungicidal, bactericidal, insecticidal, and antitumor activity.22−27 © XXXX American Chemical Society

Received: October 6, 2016

A

DOI: 10.1021/acs.inorgchem.6b02387 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry have been prepared.30−32 Since amino acids that have been converted into dithiocarbamates (dtcs) contain two different potentially bidentate coordination functions, we initiated a research project aiming at the exploration of the macro- and supramolecular chemistry of metal−organic assemblies derived from diorganotin building blocks and dtc-functionalized amino acids. In combination with metals having two unoccupied coordination sites, ligands containing two different metalcoordinating functions can generate complexes with homo- or hetero-ditopic ligand coordination. In the context of metallamacrocyclic chemistry, thus, various options arise for coordination-driven assemblies as illustrated in Scheme 1 for

significantly the supramolecular structure, providing either variations in the 3D organization,52 shape of the macrocyclic cavity,53 or dimension of the molecular cage, [2 + 2] versus [3 + 3] assembly.54 By means of a combined experimental and theoretical study, the compound series reported herein enabled us to examine the odd−even effects in dinuclear metallamacrocycles derived from a homologous series of dtc-functionalized amino acids.

2. EXPERIMENTAL SECTION Instrumental. Microwave-assisted reactions were performed in a monomode microwave CEM Discover apparatus with a power output ranging from 0 to 300 W using sealed vessels equipped with condensers. IR spectra were recorded on Bruker Vector 22 FT and Nicolet 6700 FT-IR spectro-photometers. NMR studies were performed with Varian Gemini 200 and Varian Inova 400 instruments. Standard references were used: tetramethylsilane (TMS; δ1H = 0, δ13C = 0) and SnMe4 (δ119Sn = 0). To elucidate the structures of the compounds, 2D homo- and heteronuclear correlation spectra (COSY and HSQC) were performed for representative samples ([Me2Sn(L4Bn)]2, [nBu2Sn(L5-Bn)]2, and [Ph2Sn(L7-Bn)]2) to assign the 1H and 13 C NMR spectra correctly. Electrospray ionization time-of-flight (ESITOF) mass spectra were obtained on an Agilent Technologies ESITOF equipment. Preparative Part. Dimethyltin dichloride, di-n-butyltin dichloride, diphenyltin dichloride, 5-aminopentanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, isovaleraldehyde, benzaldehyde, and sodium cyanoborohydride were commercially available and were used without further purification. The monoalkylated secondary amines Nbenzyl-5-aminopentanoic acid, N-benzyl-6-aminohexanoic acid, Nisopentyl-7-aminoheptanoic acid, N-isopentyl-8-aminooctanoic acid, N-isopentyl-11-aminoundecanoic acid, and N-isopentyl-12-aminododecanoic acid were prepared by microwave-assisted reactions according to a reported methodology by combination of the corresponding amino acid with either benzaldehyde or isovaleraldehyde followed by reduction with sodium cyanoborohydride.55 For the preparation of complexes 1−18 a common synthetic procedure was used, which is therefore given in detail only for compounds 1−3. Safety Note. Caution! Diorganotin compounds may af fect the immune system on repeated exposure. Dibutyltin compounds may have a corrosive or irritant ef fect on skin and eyes and may be toxic to reproduction or mutagenic.22−27 [Me2Sn(L4-Bn)]2 (1). For the preparation of [Me2Sn(L4-Bn)]2, Nbenzyl-5-aminopentanoic acid (0.100 g, 0.48 mmol) and 2 equiv of KOH (0.054 g, 0.96 mmol) were dissolved in ethanol (30 mL), whereupon an excess of carbon disulfide (2 mL) was added. After the mixture was stirred for 2 h at room temperature, a solution of one equiv of dimethyltin dichloride (0.106 mg, 0.48 mmol) in ethanol (10 mL) was added, giving almost immediately a white precipitate. After the solution was stirred for 12 h, the precipitate was separated by filtration and washed with water and hot hexane. Recrystallization from a mixture of dichloromethane and absolute ethanol (1:1 v/v) gave crystals suitable for single-crystal X-ray diffraction analysis. Yield: 0.102 g (49%). mp 174−175 °C. IR (KBr): ṽ = 2926 (w), 1604 νas(OCO) (m), 1563 (m), 1482 ν(N-CSS) (m), 1452 (m), 1416 (s), 1352 (m), 1303 (m), 1238 (m), 1199 (m), 1137 (m), 1086 (m), 1029 (w), 966 νas(CSS) (m), 908 (m), 786 (s), 730 (s), 697 (s) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 1.16 (s, 12H, Sn-CH3,2JSn−H= 79 Hz), 1.51−1.68 (m, 8H, CH2−CH2-CH2-CH2), 2.21 (t, 4H, CH2-COO), 3.61 (t, 4H, N-CH2-CH2), 4.96 (s, 4H, N-CH2-Ph), 7.19−7.31 (m, 10H, C6H5) ppm. 13C NMR (100 MHz, CDCl3, 20 °C, TMS): δ = 8.4 (Sn-CH3), 22.8 (C4), 26.2 (C3), 36.0 (CH2-COO), 53.6 (N-CH2CH2), 57.2 (N-CH2-Ph), 127.7, 128.3, 128.9 (o,m,p-C6H5), 134.4 (iC6H5), 179.6 (COO), 199.4 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −224 ppm. High-resolution MS (ESI+-

Scheme 1. Schematic Representation of the Four Possible Types of Coordination in Dinuclear Metallamacrocycles Derived from Bifunctional Dithiocarbamate-Carboxylate Ligands

dinuclear constructs: (i) homonuclear assembly with homoditopic ligand coordination, (ii) homonuclear assembly with hetero-ditopic ligand coordination, (iii) heteronuclear assembly with homo-ditopic ligand coordination, and (iv) heteronuclear assembly with hetero-ditopic ligand coordination. Because of their importance in pharmaceutical and medicinal chemistry, amino acids have been extensively explored by organic chemists with the additional benefit that today almost the complete series of aliphatic amino acids is commercially available, H2N−(CH2)x−COOH with x = 1, 2, 3, 4, 5, 6, 7, 10, and 11. In metal−organic assemblies, homologous series of difunctional ligands enable to modulate systematically the size of the cavity, which is particularly relevant for molecular recognition.33−42 In continuation of a previous report on a series of macrocyclic and polymeric diorganotin complexes obtained from dtc-functionalized α-, β-, and γ-amino acids,43 we report now on a second series of 18 diorganotin complexes based on this type of ligands but containing a larger number of methylene groups in the aliphatic spacer between the metalcoordinated carboxylate and dtc functions, −S2CN(R)− (CH2)x−COO−, with x = 4, 5, 6, 7, 10, and 11; R = benzyl (Bn) or isopentyl (iPen). The physical properties of homologous series of alkane derivatives are frequently propense to odd−even effects, particularly in solid-state aggregates. The probably best known phenomenon is the anomality of the melting points of linear alkanes, giving a zigzag type of graph with increasing aliphatic chain length.44 Fatty acids,45α,ω-alkanedicarboxylic acids,46−48α,ω-alkanediols,49α,ω-alkanedithiols,50α,ω-alkanediamines,49 and bis(pyridylcarboxamido)alkanes51 constitute further examples. More recently, odd−even dependent effects have been documented also for two-component molecular crystals,52 macrocyclic palladium(II) bis-dithiocarbamates,53 and the assembly of cage molecules formed through reversible covalent bonds.54 In all cases, the odd−even effect influenced B


Article

Inorganic Chemistry TOF) for C 30 H 42 N 2 NaO 4 S 4 Sn 2 (884.976 967): m/z (%) = 884.972 919 (M+Na, 10; error: −4.6 ppm). [nBu2Sn(L4-Bn)]2 (2). For the preparation of [nBu2Sn(L4-Bn)]2, Nbenzyl-5-aminopentanoic acid (0.100 g, 0.48 mmol) and two equiv of KOH (0.054 g, 0.96 mmol) were dissolved in ethanol (30 mL), whereupon an excess of carbon disulfide (2 mL) was added. After the mixture was stirred for 2 h at room temperature, a solution of one equiv of di-n-butyltin dichloride (0.147 mg, 0.48 mmol) in ethanol (10 mL) was added. After the solution was stirred for 12 h, the solvent was removed in vacuo, and the product was extracted with dichloromethane to give a light yellow viscous substance. Yield: 0.186 g (75%). IR (KBr): ṽ = 2954 (w), 2922 (w), 2868 (w), 1603 νas(OCO) (w), 1563 (w), 1495 ν(N-CSS) (w), 1478 (w), 1453 (w), 1415 (m), 1373 (m), 1301 (w), 1306 (m), 1238 (m), 1195 (w), 1139 (m), 1077 (w), 1029 (w), 964 νas(SCS) (m), 877 (w), 729 (s), 695 (s) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.93 (t, 12H, δ-CH3), 1.24−1.81 (m, 32H, α-CH2, β-CH2, γ-CH2, CH2−CH2-CH2-CH2), 2.26 (t, 4H, CH2-COO), 3.67 (t, 4H, N-CH2-CH2), 5.04 (s, 4H, NCH2-Ph), 7.25−7.32 (m, 10H, C6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 14.0 (δ-CH3), 23.0 (C4), 26.6 (C3, γ-CH2), 28.1 (α-CH2, β-CH2), 35.1 (CH2-COO), 54.1 (N-CH2-CH2), 57.4 (NCH2-Ph), 127.8, 128.4, 129.1 (o,m,p-C6H5), 134.9 (i-C6H5), 179.9 (COO), 200.4 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −232 ppm. High-resolution MS (ESI+ -TOF) for C 4 2 H 6 6 N 2 NaO 4 S 4 Sn 2 (calcd. 1053.184 979): m/z (%) = 1053.181 670 (M+Na, 13; error −3.1 ppm). [Ph2Sn(L4-Bn)]2 (3). For the preparation of [Ph2Sn(L4-Bn)]2, Nbenzyl-5-aminopentanoic acid (0.100 g, 0.48 mmol) and 2 equiv of KOH (0.054 g, 0.96 mmol) were dissolved in ethanol (30 mL), whereupon an excess of carbon disulfide (2 mL) was added. After the mixture was stirred for 2 h at room temperature, a solution of one equiv of diphenyltin dichloride (0.166 mg, 0.48 mmol) in ethanol (10 mL) was added, giving almost immediately a white precipitate. After the solution was stirred for 12 h, the precipitate was separated by filtration and washed with water and hot hexane. Yield: 0.225 g (84%). mp 222−225 °C. IR (KBr): ṽ = 2932 (w), 1643 νas(OCO) (s), 1514 ν(N-CSS) (m), 1431 (m), 1376 (m), 1358 (m), 1291 (m), 1258 (m), 1215 (s), 1188 (w), 1131 (w), 1088 (w), 1071 (w), 998 νas(SCS) (w), 963 (w), 736 (s), 702 (s), 693 (s) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δν = 1.64 (br, 8H, CH2−CH2-CH2-CH2), 2.30 (br, 4H, CH2-COO), 3.61 (br, 4H, N-CH2-CH2), 4.93 (s, 4H, N-CH2-Ph), 7.26−7.42 (m, 22H, CH2−C6H5, m-SnC6H5, p-SnC6H5), 7.96 (d, 8H, 3 JSn−H = 85 Hz, o-SnC6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 23.2 (C4), 26.7 (C3), 35.3 (CH2-COO), 54.9 (N-CH2CH2), 58.3 (N-CH2-Ph), 128.1, 128.6, 129.0, 129.2, 130.0 (o,m,pCH2C6H5, m,p-SnC6H5), 134.3 (i-CH2C6H5), 135.8 (o-SnC6H5, 2JSn−C = 61 Hz), 142.7 (i-SnC6H5), 178.8 (COO), 198.4 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −370 ppm. Highresolution MS (ESI + -TOF) for C 50 H 51 N 2 O 4 S 4 Sn 2 (calcd. 1111.078 142): m/z (%) = 1111.058 353 (M+H, 0.9; error −17.8 ppm). [Me2Sn(L5-Bn)]2 (4). This compound was obtained in form of a white precipitate using the procedure described for [Me2Sn(L4-Bn)]2. Yield: 0.171 g (85%). mp 153−155 °C. IR (KBr): ṽ = 2931 (m), 2860 (w), 1728 (w), 1621 νas(OCO) (s), 1496 ν(N-CSS) (s), 1428 (s), 1369 (s), 1249 (m), 1134 (w), 1079 (w), 981 νas(CSS) (w), 787 (m), 738 (w), 699 (w), 637 (w), 567 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 1.19 (s, 12H, Sn-CH3,2JSn−H = 79 Hz), 1.19−1.71 (m, 12H, CH2−CH2-CH2-CH2-CH2), 2.21 (t, 4H, CH2COO), 3.63 (t, 4H, N-CH2-CH2), 4.99 (s, 4H, N-CH2-Ph), 7.22−7.41 (m, 10H, C6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 9.0 (Sn-CH3), 25.1 (C4), 26.5 (C3), 31.2 (C5), 34.9 (CH2-COO), 54.3 (N-CH2-CH2), 58.1 (N-CH2-Ph), 128.0, 128.5, 129.2 (o,m,pC6H5), 134.4 (i-C6H5), 180.1 (COO), 199.6 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −222 ppm. High-resolution MS (ESI+-TOF) for C32H47N2O4S4Sn2 (calcd. 891.045 720): m/z (%) = 891.045 643 (M+H, 11; error −0.1 ppm). [nBu2Sn(L5-Bn)]2 (5). This compound was prepared using the procedure described for [nBu2Sn(L4-Bn)]2. Recrystallization from a mixture of dichloromethane and absolute ethanol (1:4 v/v) gave light

yellow crystals suitable for single-crystal X-ray diffraction analysis. Yield: 0.208 g (87%). mp 101−103 °C. IR (KBr): ṽ = 2956 (s), 2925 (s), 2856 (m), 1728 (w), 1607 νas(OCO) (m), 1496 ν(N-CSS) (s), 1453 (s), 1425 (s), 1377 (s), 1242 (w), 1234 (m), 1204 (m), 1135 (w), 1078 (w), 1045 (w), 1030 (w), 978νas(CSS) (w), 878 (w), 730 (m), 699 (m), 600 (w), 528 (w), 456 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.93 (t, 12H, δ-CH3), 1.24−1.79 (m, 36H, α-CH2, β-CH2, γ-CH2, CH2−CH2-CH2-CH2-CH2), 2.21 (t, 4H, CH2COO), 3.64 (t, 4H, N-CH2-CH2), 5.02 (s, 4H, N-CH2-Ph), 7.24−7.35 (m, 10H, C6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 13.8 (δ-CH3), 25.3, 26.3 (C3, C4, C5, γ-CH2), 27.8 (α-CH2, β-CH2), 35.3 (CH2-COO), 54.0 (N-CH2-CH2), 57.4 (N-CH2-Ph), 127.6, 128.2, 128.9 (o,m,p-C6H5), 134.7 (i-C6H5), 180.2 (COO), 199.9 (CSS) ppm. 119 Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −231 ppm. Highresolution MS (ESI + -TOF) for C 44 H 71 N 2 O 4 S 4 Sn 2 (calcd. 1059.234 416): m/z (%) = 1059.237 026 (M+H, 0.3; error +2.5 ppm). [Ph2Sn(L5-Bn)]2 (6). This compound was obtained in form of a white precipitate using the procedure described for [Ph2Sn(L4-Bn)]2. Yield: 0.189 g (74%). mp 125−127 °C. IR (KBr): ṽ = 3054 (m), 2932 (m), 2860 (m), 1723 (m), 1638 νas(OCO) (s), 1498 ν(N-CSS) (m), 1431 (s), 1366 (m), 1297 (m), 1240 (m), 1133 (m), 1072 (m), 977 νas(SCS) (w), 734 (s), 693 (s), 651 (m), 448 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 1.24−1.66 (m, 12H, CH2−CH2CH2-CH2-CH2), 2.25 (t, 4H, CH2-COO), 3.57 (m, 4H, N-CH2-CH2), 4.93 (s, 4H, N-CH2-Ph), 7.21−7.52 (m, 22H, CH2−C6H5, m-SnC6H5, p-SnC6H5), 7.93 (d, 8H, 3JSn−H = 83 Hz, o-SnC6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 25.0 (C5), 26.3 (C3, C4), 35.1 (CH2-COO), 55.0 (N-CH2-CH2), 58.9 (N-CH2-Ph), 127.8, 128.5, 128.8, 129.1, 130.3 (o,m,p-CH2C6H5, m,p-SnC6H5), 134.0 (iCH2C6H5), 135.7 (o-SnC6H5, 2JSn−C = 61 Hz), 142.5 (i-SnC6H5), 178.8 (COO), 197.7 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −369 ppm. High-resolution MS (ESI+-TOF) for C52H55N2O4S4Sn2 (calcd. 1139.109 525): m/z (%) = 1139.092 624 (M +H, 1; error −14.8 ppm). [Me2Sn(L6-iPen)]2 (7). This compound was obtained in the form of a white precipitate using the procedure described for [Me2Sn(L4Bn)]2. Yield: 0.177 g (87%). mp 144−146 °C. IR (KBr): ṽ = 2932 (s), 2860 (m), 1725 (m), 1608 νas(OCO) (m), 1501 ν(N-CSS) (s), 1461 (m), 1429 (m), 1367 (m), 1300 (m), 1228 (m), 1091 (w), 971 νas(CSS) (w), 786 (m), 730 (w), 675 (w), 601 (w), 559 (w), 518 (w) cm−1. 1H NMR (400 MHz, CDCl3, 20 °C, TMS): δ = 0.88 (d, 12H, CHCH3), 1.13 (s, 12H, Sn-CH3,2JSn−H = 78 Hz), 1.27−1.56 (m, 22H, CH2−CH2-CH2-CH2-CH2-CH2, CH2CHCH3), 2.20 (t, 4H, CH2COO), 3.60 (t, 8H, N-CH2) ppm. 13C NMR (100 MHz, CDCl3, 20 °C, TMS): δ = 8.9 (Sn-CH3), 22.4 (CHCH3), 25.4, 26.4, 26.6, 26.8, 28.9 (C3, C4, C5, C6, CHCH3), 34.9 (C10), 35.4 (CH2-COO), 54.2, 55.5 (N-CH2), 180.5 (COO), 197.0 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −227 ppm. High-resolution MS (ESI+-TOF) for C30H59N2O4S4Sn2 (calcd. 879.139 976): m/z (%) = 879.133 450 (M+H, 5; error −7.4 ppm). [nBu2Sn(L6-iPen)]2 (8). This compound was obtained in the form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.180 g (74%). IR (KBr): ṽ = 2957 (s), 2866 (s), 1730 (m), 1616 νas(OCO) (m), 1500 ν(N-CSS) (s), 1460 (s), 1430 (s), 1371 (s), 1299 (m), 1227 (m), 1119 (w), 1086 (w), 1026 (w), 969 νas(CSS) (w), 876 (w), 767 (w), 682 (w), 601 (w), 528 (w), 458 (w) cm−1. 1H NMR (400 MHz, CDCl3, 20 °C, TMS): δ = 0.87 (t, 24H, CHCH3, δ-CH3), 1.29−1.73 (m, 46H, α-CH2, β-CH2, γ-CH2, CH2−CH2-CH2-CH2-CH2-CH2, CH2CHCH3), 2.21 (t, 4H, CH2COO), 3.62 (t, 8H, N-CH2) ppm. 13C NMR (100 MHz, CDCl3, 20 °C, TMS): δ = 13.7 (δ-CH3), 22.5 (CHCH3), 25.4, 26.3, 26.4, 26.6, 26.9 (C3, C4, C5, C6, CHCH3, γ-CH2), 28.4, 28.9 (α-CH2, β-CH2), 34.9 (C10), 35.5 (CH2-COO), 54.1, 55.3 (N-CH2), 179.9 (COO), 197.6 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −236 ppm. High-resolution MS (ESI+-TOF) for C42H83N2O4S4Sn2 (calcd. 1047.327 421): m/z (%) = 1047.327 202 (M+H, 14; error −0.2 ppm). [Ph2Sn(L6-iPen)]2 (9). This compound was obtained in form of a white precipitate using the procedure described for [Ph2Sn(L4-Bn)]2. Yield: 0.228 g (87%). mp 91−92 °C. IR (KBr): ṽ = 3049 (w), 2955 C


Article

Inorganic Chemistry (m), 2931 (m), 2860 (w), 1719 (w), 1638 νas(OCO) (m), 1509 ν(NCSS) (s), 1459 (w), 1431 (s), 1401 (m), 1300 (w), 1228 (w), 1189 (w), 1118 (w), 1068 (w), 1021 (w), 996 (w), 967 νas(SCS) (w), 731 (s), 694 (s), 621 (w), 448 (m) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.84 (d, 12H, CHCH3), 1.22−1.57 (m, 22H, CH2− CH2-CH2-CH2-CH2-CH2, CH2CHCH3), 2.25 (t, 4H, CH2-COO), 3.55 (m, 8H, N-CH2), 7.31−7.43 (m, 12H, m-SnC6H5, p-SnC6H5), 7.91 (d, 8H, 3JSn−H = 83 Hz, o-SnC6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 22.5 (CHCH3), 25.4, 26.5, 26.6, 26.9, 28.8 (C3, C4, C5, C6, CHCH3), 34.9 (C10), 35.4 (CH2-COO), 55.1, 56.3 (N-CH2), 128.8 (m-SnC6H5), 130.0 (o-SnC6H5), 135.8 (o-SnC6H5, 2JSn−C = 60 Hz), 142.5 (i-SnC6H5), 179.8 (COO), 195.5 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −374 ppm. High-resolution MS (ESI+-TOF) for C50H67N2O4S4Sn2 (calcd. 1127.203 352): m/z (%) = 1127.202 285 (M+H, 6; error −0.9 ppm). [Me2Sn(L7-iPen)]2 (10). This compound was obtained in form of a white precipitate using the procedure described for [Me2Sn(L4-Bn)]2. Yield: 0.142 g (72%). mp 178−179 °C. IR (KBr): ṽ = 2930 (s), 2860 (m), 1725 (w), 1619 νas(OCO) (m), 1502 ν(N-CSS) (s), 1431 (s), 1370 (m), 1299 (m), 1265 (m), 1093 (w), 973 νas(CSS) (w), 790 (m), 728 (w), 625 (w), 558 (w), 519 (w) cm−1. 1H NMR (400 MHz, CDCl3, 20 °C, TMS): δ = 0.88 (d, 12H, CHCH3), 1.13 (s, 12H, SnCH3), 1.26−1.55 (m, 26H, CH2−CH2-CH2-CH2-CH2-CH2-CH2, CH2CHCH3), 2.21 (t, 4H, CH2-COO), 3.58 (t, 8H, N-CH2) ppm. 13 C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 8.9 (Sn-CH3), 22.5 (CHCH3), 25.6, 26.4, 26.7, 26.9, 29.0, 29.2 (C3, C4, C5, C6, C7, CHCH3,), 35.0, 35.3 (C11, CH2-COO), 54.2, 55.5 (N-CH2), 181.0 (COO), 196.4 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −228 ppm. High-resolution MS (ESI+ -TOF) for C32H63N2O4S4Sn2 (calcd. 907.170 920): m/z (%) = 907.170 453 (M +H, 14; error −0.52 ppm). [nBu2Sn(L7-iPen)]2 (11). This compound was obtained in form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.194 g (83%). IR (KBr): ṽ = 2957 (s), 2859 (s), 1726 (w), 1617 νas(OCO) (m), 1500 ν(N-CSS) (m), 1461 (m), 1430 (m), 1373 (m), 1297 (w), 1244 (w), 1173 (w), 1120 (w), 1087 (w), 1024 (w), 970 νas(CSS) (w), 876 (w), 681 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.87 (t, 24H, CHCH3, δ-CH3), 1.29−1.76 (m, 50H, α-CH2, β-CH2, γ-CH2, CH2−CH2-CH2-CH2-CH2CH2-CH2, CH2CHCH3), 2.24 (t, 4H, CH2-COO), 3.63 (t, 8H, NCH2) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 13.9 (δCH3), 22.5 (CHCH3), 25.7, 26.4, 26.7, 26.9, 27.9, 28.3, 29.0, 29.3 (C3, C4, C5, C6, C7, CHCH3, α-CH2, β-CH2, γ-CH2), 35.0, 35.3 (C11, CH2-COO), 54.1, 55.3 (N-CH2), 181.9 (COO), 197.1 (CSS) ppm. 119 Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −236 ppm. Highresolution MS (ESI + -TOF) for C 44 H 87 N 2 O 4 S 4 Sn 2 (calcd. 1075.358 721): m/z (%) = 1075.358 083 (M+H, 19; error −0.6 ppm). [Ph2Sn(L7-iPen)]2 (12). This compound was obtained in the form of a white precipitate using the procedure described for [Ph2Sn(L4Bn)]2. Recrystallization from a mixture of chloroform and absolute ethanol (1:1 v/v) gave crystals suitable for single-crystal X-ray diffraction analysis. Yield: 0.229 g (91%). mp 166−168 °C. IR (KBr): ṽ = 3048 (w), 2957 (s), 2930 (s), 2859 (m), 1722 (w), 1642 νas(OCO) (m), 1510 ν(N-CSS) (s), 1431 (s), 1369 (m), 1300 (w), 1238 (w), 1189 (w), 1119 (w), 1069 (w), 1022 (w), 996 (w), 969 νas(SCS) (w), 731 (s), 694 (s), 622 (w), 449 (m) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.84 (d, 12H, CHCH3), 1.20− 1.63 (m, 26H, CH2−CH2-CH2-CH2-CH2-CH2-CH2, CH2CHCH3), 2.22 (t, 4H, CH2-COO), 3.60 (m, 8H, N-CH2), 7.31−7.37 (m, 12H, m-SnC6H5, p-SnC6H5), 7.85 (d, 8H, 3JSn−H = 85 Hz, o-SnC6H5) ppm. 13 C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 22.3 (CHCH3), 25.6, 26.3, 26.5, 26.9, 28.9, 29.0 (C3, C4, C5, C6, C7, CHCH3), 35.1 (C11), 35.6 (CH2-COO), 54.6, 56.1 (N-CH2), 128.6 (m-SnC6H5), 129.7 (oSnC6H5), 135.6 (o-SnC6H5, 2JSn−C = 59 Hz), 142.8 (i-SnC6H5), 179.5 (COO), 195.8 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −372 ppm. High-resolution MS (ESI+ -TOF) for C52H71N2O4S4Sn2 (calcd. 1155.233 524): m/z (%) = 1155.227 150 (M+H, 6; error −5.5 ppm). [Me2Sn(L10-iPen)]2 (13). This compound was obtained in the form of a light yellow viscous substance using the procedure described for

[nBu2Sn(L4-Bn)]2. Yield: 0.171 g (94%). IR (KBr): ṽ = 2927 (s), 2855 (m), 1728 (m), 1615 νas(OCO) (m), 1504 ν(N-CSS) (s), 1432 (s), 1370 (m), 1300 (m), 1239 (m), 1097 (w), 972 νas(CSS) (w), 786 (m), 626 (w), 556 (w), 517 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.87 (d, 12H, CHCH3), 1.15 (s, 12H, Sn-CH3), 1.21 and 1.49−1.66 (m, 38H, CH2−CH2-CH2-CH2-CH2-CH2-CH2-CH2CH2-CH2, CH2CHCH3), 2.22 (t, 4H, CH2-COO), 3.56 (t, 8H, NCH2) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 9.4 (SnCH3), 22.5 (CHCH3), 25.7, 26.4, 26.8, 29.4 (C3, C4, C5, C6, C7, C8, C9, C10, CHCH3), 34.9, 35.3 (C14, CH2-COO), 54.3, 55.6 (N-CH2), 182.3 (COO), 196.1 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −228 ppm. High-resolution MS (ESI+-TOF) for C38H75N2O4S4Sn2 (calcd. 991.265 485): m/z (%) = 991.247 864(M +H, 2; error −17.7 ppm). [nBu2Sn(L10-iPen)]2 (14). This compound was obtained in the form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.197 g (92%). IR (KBr): ṽ = 2926 (s), 2858 (m), 1724 (w), 1609 νas(OCO) (m), 1502 ν(N-CSS) (m), 1456 (m), 1378 (m), 1296 (w), 1096 (w), 970 νas(CSS) (w), 876 (w), 682 (w), 503 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.88 (t, 24H, CHCH3, δ-CH3), 1.23−1.76 (m, 62H, α-CH2, β-CH2, γ-CH2, CH2−CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2, CH2CHCH3), 2.23 (t, 4H, CH2-COO), 3.61 (t, 8H, N-CH2) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 13.9 (δ-CH3), 22.5 (CHCH3), 25.1, 25.7, 26.4, 26.8, 27.9, 28.5, 29.0, 29.4 (C3, C4, C5, C6, C7, C8, C9, C10, CHCH3, α-CH2, β-CH2, γ-CH2), 35.0, 35.3 (C14, CH2-COO), 54.1, 55.4 (N-CH2), 181.7 (COO), 196.9 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −237 ppm. High-resolution MS (ESI+-TOF) for C50H99N2O4S4Sn2 (calcd. 1159.452 622): m/z (%) = 1159.443 461 (M+H, 5; error −7.9 ppm). [Ph2Sn(L10-iPen)]2 (15). This compound was obtained in the form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.213 g (93%). IR (KBr): ṽ = 3053 (w), 2927 (s), 2856 (m), 1715 (w), 1640 νas(OCO) (w), 1511 ν(N-CSS) (s), 1433 (s), 1370 (m), 1299 (w), 1238 (w), 1098 (w), 968 νas(SCS) (w), 731 (s), 693 (m), 615 (w), 448 (m) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.86 (d, 12H, CHCH3), 1.19−1.54 (m, 3 8H, CH 2 − CH 2 -CH 2 -C H 2 - CH 2 -CH 2 -C H 2 - CH 2 -C H 2 - CH 2 , CH2CHCH3), 2.28 (t, 4H, CH2-COO), 3.57 (m, 8H, N-CH2), 7.29−7.37 (m, 12H, m-SnC6H5, p-SnC6H5), 7.91 (d, 8H, 3JSn−H = 84 Hz, o-SnC6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 22.5 (CHCH3), 25.4, 25.9, 26.4, 26.9, 29.3 (C3, C4, C5, C6, C7, C8, C9, C10, CHCH3), 34.4, 35.3 (C14, CH2-COO), 55.2, 56.6 (N-CH2), 128.8 (m-SnC6H5), 130.1 (o-SnC6H5), 135.7 (o-SnC6H5, 2JSn−C = 63 Hz), 142.2 (i-SnC6H5), 182.7 (COO), 195.0 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −373 ppm. High-resolution MS (ESI+-TOF) for C58H83N2O4S4Sn2 (calcd. 1239.327 425): m/z (%) = 1239.329 302 (M+H, 6; error 1.5 ppm). [Me2Sn(L11-iPen)]2 (16). This compound was obtained in form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.140 g (79%). IR (KBr): ṽ = 2930 (s), 2859 (m), 1727 (m), 1618 νas(OCO) (m), 1506 ν(N-CSS) (s), 1432 (m), 1370 (m), 1300 (m), 1238 (m), 1093 (w), 972 νas(CSS) (w), 787 (m), 556 (w), 518 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.87 (d, 12H, CHCH3), 1.08 (s, 12H, Sn-CH3), 1.19 and 1.51 (m, 42H, CH2−CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2CH2, CH2CHCH3), 2.15 (t, 4H, CH2-COO), 3.58 (t, 8H, N-CH2) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 8.5 (Sn-CH3), 22.7 (CHCH3), 25.8, 26.4, 26.8, 27.4, 29.5 (C3, C4, C5, C6, C7, C8, C9, C10, C11, CHCH3), 35.3, 35.6 (C15, CH2-COO), 54.1, 55.5 (NCH2), 181.0 (COO), 196.8 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −228 ppm. High-resolution MS (ESI+-TOF) for C40H79N2O4S4Sn2 (calcd. 1019.296 865): m/z (%) = 1019.298 309 (M +H, 7; error +1.4 ppm). [nBu2Sn(L11-iPen)]2 (17). This compound was obtained in form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.184 g (89%). IR (KBr): ṽ = 2922 (s), 2866 (s), 1728 (s), 1608 νas(OCO) (m), 1502 ν(N-CSS) (s), 1461 (s), 1431 (s), 1371 (s), 1298 (m), 1243 (m), 1173 (m), 1120 (w), 1090 (w), 1026 (w), 967 νas(CSS) (w), 876 (w), 804 (w), 768 (w), 682 D


Article

Inorganic Chemistry (w), 530 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.80 (t, 24H, CHCH3, δ-CH3), 1.15−1.66 (m, 66H, α-CH2, β-CH2, γCH 2 , CH 2 −CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 , CH2CHCH3), 2.08 (t, 4H, CH2-COO), 3.60 (t, 8H, N-CH2) ppm. 13 C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 13.8 (δ-CH3), 22.4 (CHCH3), 24.1, 25.8, 26.4, 26.5, 26.8, 27.9, 29.4 (C3, C4, C5, C6, C7, C8, C9, C10, C11, CHCH3, α-CH2, β-CH2, γ-CH2), 35.2, 35.5 (C15, CH2-COO), 53.8, 55.2 (N-CH2), 180.8 (COO), 197.5 (CSS) ppm. 119 Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −236 ppm. Highresolution MS (ESI + -TOF) for C 52 H 103 N 2 O 4 S 4 Sn 2 (calcd. 1187.485 157): m/z (%) = 1187.485 162 (M+H, 6; error +0.1 ppm). [Ph2Sn(L11-iPen)]2 (18). This compound was obtained in the form of a light yellow viscous substance using the procedure described for [nBu2Sn(L4-Bn)]2. Yield: 0.169 g (76%). IR (KBr): ṽ = 2930 (s), 2859 (w), 1721 (w), 1639 νas(OCO) (m), 1510 ν(N-CSS) (m), 1460 (m), 1430 (m), 1400 (s), 1300 (w), 1118 (w), 1022 (w), 968 νas(SCS) (w), 731 (m), 694 (m), 621 (w), 448 (w) cm−1. 1H NMR (200 MHz, CDCl3, 20 °C, TMS): δ = 0.90 (d, 12H, CHCH3), 1.24−1.58 (m, 42H, CH 2 −CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 , CH2CHCH3), 2.25 (br, 4H, CH2-COO), 3.64 (br, 8H, N-CH2), 7.38 (br, 12H, m-SnC6H5, p-SnC6H5), 7.89 (d, 8H, 3JSn−H = 76 Hz, oSnC6H5) ppm. 13C NMR (50 MHz, CDCl3, 20 °C, TMS): δ = 22.5 (CHCH3), 25.9, 26.4, 26.7, 29.5 (C3, C4, C5, C6, C7, C8, C9, C10, CHCH3), 35.3, 36.1 (C15, CH2-COO), 55.0, 56.2 (N-CH2), 128.6 (mSnC6H5), 129.7 (o-SnC6H5), 135.7 (o-SnC6H5, 2JSn−C = 63 Hz), 143.0 (i-SnC6H5), 179.3 (COO), 195.9 (CSS) ppm. 119Sn NMR (75 MHz, CDCl3, SnMe4, 20 °C): δ = −374 ppm. High-resolution MS (ESI+TOF) for C60H87N2O4S4Sn2 (calcd. 1267.358 721): m/z (%) = 1267.358 317 (M+H, 21; error −0.3 ppm). X-ray Crystallography. Single-crystal X-ray diffraction studies were performed on a Bruker-APEX diffractometer with a CCD area detector (λMο Kα = 0.710 73 Å, monochromator: graphite). Frames were collected at T = 100 K for 1, 5, and 12 via ω/ϕ-rotation at 10 s per frame (SMART).56 The measured intensities were reduced to F2 and corrected for absorption with SADABS (SAINT-NT).57 Corrections were made for Lorentz and polarization effects. Structure solution, refinement, and data output were performed with the SHELXTL-NT program package.58,59 Non-hydrogen atoms were refined anisotropically, while hydrogen atoms were placed in geometrically calculated positions using a riding model. Diamond was used for the creation of figures.60 Crystallographic data for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication Nos. CCDC-1489379−1489381. Additional X-ray crystallographic information is available in the Supporting Information. Computational Details. Density functional theory (DFT) quantum chemical calculations were performed with the quantum mechanical program Gaussian 09 (version B.01),61 using the B3LYP hybrid functional62,63 in combination with the def2-TZVP basis set.64 Harmonic vibrational frequencies were computed with the same method to characterize stationary points as minima. Geometry optimizations were performed on macrocycles having both tin atoms in trans configuration. Different initial conformations were explored based on the structural charactistics established by the X-ray crystallographic analyses of 5 and 12 and by varying the connectivity of the metal-coordinating functions. In accordance with the crystallographic analysis, Ci symmetry was imposed on the macrocyclic structures with the purpose to reduce the computational cost for the geometry optimizations.

amines.28 The synthesis of the N-substituted amino acids was achieved by reductive amination.55 In analogy to the previously reported series of diorganotin complexes,43 in the case of 5aminopentanoic (x = 4) and 6-aminohexanoic acid (x = 5), a benzyl group was introduced as substituent at the nitrogen atom. However, for the amino acids having a larger number of methylene groups between the metal-coordinating functions (x = 6, 7, 10, and 11), difficulties were encountered to isolate the secondary amines in pure form. This problem could be resolved using the isopentyl group, which provided the target compounds in good yields. For the formation of the diorganotin(IV) complexes with the respective dithiocarbamate−carboxylate ligands, the corresponding N-substituted amino acid was combined with potassium hydroxide and an excess of carbon disulfide in ethanol to generate the difunctional ligand. Subsequent in situ addition of the corresponding diorganotin dichloride gave the corresponding dinuclear macrocyclic complexes 1−18 in yields ranging from 49 to 94% (Scheme 2). The resulting compounds were Scheme 2. Reaction Sequence for the Preparation of the Macrocyclic Diorganotin(IV) Complexes 1−18

characterized by IR spectroscopy, NMR (1H, 13C, 119Sn, H,1H−COSY, and 1H,13C-HSQC) spectroscopy, and highresolution electrospray ionization time-of-flight (ESI+-TOF) mass spectrometry. Representative spectroscopic and mass spectrometric data are summarized in Table 1. 1D and 2D NMR spectra for compounds [Me2Sn(L4-Bn)]2 (1), [nBu2Sn(L5-Bn)]2 (5), and [Ph2Sn(L7-iPen)]2 (12), for which single crystals suitable for X-ray diffraction analysis could be isolated, are shown in Figures S1−S15 (Supporting Information). For the remaining compounds 2−4, 6−11, and 13−18, the 1H, 13C, and 119Sn NMR spectra were included in the Supporting Information (Figures S16−S60). The IR spectra for compounds 1−18 exhibit bands characteristic for tin-coordinated carboxylate and dithiocarbamate (dtc) groups.5−21 The asymmetric stretching vibrations for the COO− and NCSS− functions were measured in the range of 1603−1643 and 964−998 cm−1, respectively. The vibrations for the N−C bonds of the dtc fragments gave values intermediate between a single and a double bond (1482−1514 cm−1), which can be attributed to the delocalization of πelectron density within the NCSS group of atoms. The 1H NMR spectra indicated the expected downfield shifts of the NCH2 and CH2COO methylene hydrogens upon coordination of the tin atoms. For the dimethyltin complexes 1, 4, and 7, the 2 JSn−H coupling constants for the Me2Sn moieties could be measured (1, 79 Hz; 4, 79 Hz; 7, 78 Hz), giving according to Lockhart’s equation calculated C−Sn−C bond angles of 130 and 128°, respectively.65 In the 13C NMR spectra, the signals corresponding to the COO and NCSS carbon atoms were downfield-shifted to δ ≈ 180 and 200 ppm, respectively. The 119 Sn NMR spectra gave signals in the range of δ = −223 to 1

3. RESULTS AND DISCUSSION 3.1. Preparation and Spectroscopic Characterization. Since secondary amines give rise to more stable dithiocarbamate complexes than primary amines, commercially available 5aminopentanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 11-aminoundecanoic acid, and 12aminododecanoic acid were first transformed into secondary E


Article

Inorganic Chemistry Table 1. Selected Spectroscopica and Mass Spectrometricb Data for Compounds 1−18 [Me2Sn(L4-Bn)]2 (1) [nBu2Sn(L4-Bn)]2 (2) [Ph2Sn(L4-Bn)]2 (3) [Me2Sn(L5-Bn)]2 (4) [nBu2Sn(L5-Bn)]2 (5) [Ph2Sn(L5-Bn)]2 (6) [Me2Sn(L6-iPen)]2 (7) [nBu2Sn(L6-iPen)]2 (8) [Ph2Sn(L6-iPen)]2 (9) [Me2Sn(L7-iPen)]2 (10) [nBu2Sn(L7-iPen)]2 (11) [Ph2Sn(L7-iPen)]2 (12) [Me2Sn(L10-iPen)]2 (13) [nBu2Sn(L10-iPen)]2 (14) [Ph2Sn(L10-iPen)]2 (15) [Me2Sn(L11-iPen)]2 (16) [nBu2Sn(L11-iPen)]2 (17) [Ph2Sn(L11-iPen)]2 (18)

δ119Sn

δ13C (dtc)

δ13C (COO)

υas (COO)

υ (N-CSS)

υa (CSS)

m/zc [M+H/Na]+

−224 −232 −370 −222 −231 −369 −227 −236 −374 −228 −236 −372 −228 −237 −373 −228 −236 −374

199.4 200.4 198.4 199.6 199.9 197.7 197.0 197.6 195.5 196.4 197.1 195.8 196.1 196.9 195.0 196.8 197.5 195.9

179.6 179.9 178.8 180.1 180.2 178.8 180.5 179.9 179.8 181.0 181.9 179.5 182.3 181.7 182.7 181.0 180.8 179.3

1604 1603 1643 1621 1607 1638 1608 1616 1638 1619 1617 1642 1615 1609 1640 1618 1608 1639

1482 1495 1514 1496 1496 1498 1501 1500 1509 1502 1500 1510 1504 1502 1511 1506 1502 1510

966 964 998 981 978 977 971 969 967 973 970 969 972 970 968 972 967 968

884.97 1053.18 1111.06 891.05 1059.24 1139.09 879.13 1047.33 1127.20 907.17 1075.36 1155.23 991.25 1159.44 1239.33 1019.30 1187.49 1267.36

a IR, inverse centimeters; NMR, CDCl3, parts per million. bESI+-TOF. cFor compounds 1 and 2, addition of NaCl resulted in a peak characteristic for the molecular ion.

Figure 1. ESI+-TOF mass spectrum for compound [Ph2Sn(L7-iPen)]2 (12) with experimental and simulated high-resolution isotope pattern for the molecular ion [M + H]+.

−237 ppm for the dimethyl- and di-n-butyltin derivatives, and in the range of δ = −369 to −374 ppm for the diphenyltin derivatives. Of these, the high-field shift of the diphenyltin complexes can be attributed to the anisotropic shielding effect of the phenyl rings bound to the tin atoms.66 The 119Sn NMR chemical shift displacements are consistent with those reported for [R2Sn(Lx-Bn)]2 (with R = Me, nBu, and Ph and x = 1, 2, and 3), where the dithiocarbamate and the carboxylate groups were coordinated in an aniso-bidentate mode to the tin atoms, giving an overall six-coordinate coordination environment of composition R2Sn(OOC)(dtc).43 The observation of only a

single 119Sn NMR signal having a chemical shift intermediate between those reported for six-coordinate diorganotin dicarboxylates 14,17,20 and diorganotin bis-dithiocarbamates11,13,21 rules out the possibility for the existence of homo-ditopic R2Sn(OOC)2 and R2Sn(dtc)2 coordination in solution (see 119Sn NMR spectra for compounds 1−18, Supporting Information). The formation of the [2 + 2] macrocyclic assemblies was further evidenced by octupole ion guided ESI+-TOF mass spectrometric analysis. For all complexes, peaks characteristic for the molecular ion were observed (Table 1 and Experimenal F


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Inorganic Chemistry Section). Additionally, high-resolution mass spectra were recorded for each complex (Figures S61−S78, Supporting Information), showing good agreement with the theoretical isotope profiles. A comparison of the experimental and calculated isotope profiles is shown representatively in Figure 1 for compound [Ph2Sn(L7-iPen)]2 (12). 3.2. Single-Crystal X-ray Diffraction Analysis. Me2Sn(L4-Bn)]2 (1), [nBu2Sn(L5-Bn)]2 (5), and [Ph2Sn(L7-iPen)]2 (12) contain an increasing number of four, five, and seven methylene groups in the aliphatic chain between the metalcoordinating dithiocarbamate and carboxylate functions. Singlecrystal X-ray diffraction analysis revealed for all three samples a hetero-ditopic coordination mode with the diorganotin fragments. However, only compounds 5 and 12 adopted dinuclear macrocyclic structures in the solid state, while compound 1 crystallized in form of a 2D coordination polymer. The most relevant crystallographic data are summarized in Table 2, and selected geometric parameters are given in Table 3.

Table 3. Selected Bond Lengths [Å], Bond Angles [deg], and Intramolecular Distances [Å] in the Crystal Structures of Compounds 1, 5,a and 12 Sn−S1 Sn···S2 Sn−O1 Sn···O2 Sn···O2B N−CS2 S1−Sn−O1 S2···Sn···O2 S1−Sn···S2 O1−Sn···O2 C−Sn−C S1−C−S2 O1−C−O2 O2···Sn···O2B Sn···O2···Sn Sn···Sn N···Nb

Table 2. Crystallographic Data for Compounds 1, 5, and 12 crystal dataa

1

5

12

formula MW (g mol−1) crystal system space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z μ (mm−1) ρcalcd (g cm−3) b,c R Rwd,e GOF

C15H21NO2S2Sn 430.14

C44H70N2O4S4Sn2 1056.64

C52H70N2O4S4Sn2 1152.72

monoclinic

triclinic

triclinic

P21/c 14.704(2) 8.0714(13) 14.564(2) 90 93.626(3) 90 1725.0(4) 4 1.726 1.656

P1̅ 10.1984 (9) 14.2488 (13) 17.5947 (16) 99.675 (2) 90.719 (2) 107.102 (1) 2403.7(4) 2 1.254 1.460

P1̅ 9.8485(12) 11.0976(13) 13.4088(16) 71.440(2) 85.071(2) 71.243(2) 1315.3(3) 1 1.153 1.455

0.0706 0.1602 1.118

0.0293 0.0694 1.055

0.0321 0.0814 1.068

1

5A

5B

12

2.530(2) 2.804(2) 2.169(6) 2.703(7) 2.865(7) 1.348(11) 82.10(17) 158.53(16) 67.40(7) 51.99(22) 151.9(4) 119.2(5) 120.6(9) 73.16(20) 106.83(22) 6.92

2.4743(7) 2.7482(8) 2.142(2) 2.816(3)

2.4813(7) 2.7563(8) 2.154(2) 2.708(3)

2.4928(9) 2.7509(9) 2.167(2) 2.748(2)

1.324(4) 81.62(5) 159.09(5) 68.65(2) 50.75(10) 132.35(12) 117.43(16) 121.8(3)

1.326(4) 83.04(5) 155.85(5) 68.54(2) 52.70(10) 138.28(11) 117.84(16) 122.1(3)

1.323(4) 78.77(7) 161.16(7) 68.41(3) 51.75(10) 135.23(13) 116.9(2) 121.7(3)

6.84 10.28

6.69 10.33

8.15 11.32

a

The asymmetric unit contains two crystallographically independent molecules (5A and 5B). bTransannular distance.

distorted pentagonal-bipyramidal with the organic substituents in axial positions. Considering that the 119Sn NMR spectrum of compound 1 in solution gave a chemical shift typical for a six-coordinate skewed-trapezoidal bipyramidal coordination environment similar to that observed for the remaining complexes examined herein (vide supra), it becomes evident that the Sn···O contacts are dissociated in solution, giving a structure being different from that found in the solid state. This is further supported by the C−Sn−C bond angle of 130° calculated from the 2JSn−H coupling constants of the Me2Sn moiety in the 1H NMR spectrum (vide supra), which is significantly smaller than that observed in the crystal structure of 1, 151.9(4)°. DFT calculations for the macrocyclic [2 + 2] assembly of [Me2Sn(L4-Me)]2 gave a C−Sn−C bond angle of 132.3° (vide infra), suggesting that 1 probably exhibits a dinuclear macrocyclic structure in solution, as it occurs for the remaining compounds. A similar phenomenon has been reported previously based on a combined spectroscopic and solid-state structure analysis for a diorganotin dicarboxylate derived from cis-1,4-cyclohexanedicarboxylic acid that exhibited supramolecular isomerism in form of a macrocyclic and a 2D polymeric structure.67 The carboxylate bridging between the tin atoms connects neighboring polymeric strands, thereby generating 40-membered macrocycles composed of six metal atoms (Figure S79a, Supporting Information). Thus, the crystal structure of compound 1 consists indeed of a 2D network of macrocycles, which are organized in a herringbone-type arrangement parallel to bc (Figure S79b, Supporting Information). The hexanuclear assemblies are centrosymmetric with transannular Sn···Sn distances of 5.61, 11.78, and 13.09 Å. Regarding the ligand conformation, the CH2−CH2−CH2−CH2 and CH2−CH2− CH2−Ndtc fragments have torsion angles of 175.4(7) and 178.3(7)°, respectively, while the CH2−CH2−CH2−COO torsion angle is 68.7(10)°. The torsion of 51.4° between the mean planes of the dtc and carboxylate functions enable the helical topology of the 1D strands (Figure 2c). In the third

λMo Kα = 0.710 73 Å, T = 100 K. bF0 > 4σ(F0). cR = ∑||F0| − |Fc||/∑| F0|. dAll data. eRw = [∑w(F02 − Fc2)2/∑w(F02)2]1/2.

a

Although the ESI-TOF mass spectrum exhibited a relatively intense peak at m/z = 884.97 corresponding to the dimeric [2 + 2] species, compound [Me2Sn(L4-Bn)]2 (1) crystallized in form of a coordination polymer containing infinite 1D helical strands along b (Figure 2a). The dithiocarbamate groups are coordinated each to a single metal center in an anisobidentate coordination mode, while the carboxylate functions are bridged in a η2,η1 mode between two metal centers of neighboring helical strands, generating four-membered Sn2O2 cycles and an overall 2D coordination polymer (Figure 2b). Thus, in compound 1 the carboxylate groups form three bonds with two tin atoms, one short bond of 2.169(6) Å, and two longer bonds of 2.703(7) and 2.865(7) Å. This coordination mode is frequently observed in diorganotin dicarboxylates of the composition R2Sn(COO)2.14,20 The Sn−S/Sn···S bond distances with the dithiocarbamate function are 2.530(2) and 2.804(2) Å, respectively. Taking into account the Sn···O interactions, the tin coordination geometry is best described as G


Article

Inorganic Chemistry

Figure 2. Fragments of the crystal structure of Me2Sn(L4-Bn)]2 (1), showing the helical strands formed along b (a), the coordination sphere around the tin atoms giving rise to the Sn2O2 motif (b), and the angle formed between the mean planes of the dtc and carboxylate functions of the ligand in the coordination polymer (c).

Figure 3. (a) Perspective view of one of the two crystallographically independent molecular structures (5A according to Table 3) found in the crystal structure of compound [nBu2Sn(L5-Bn)]2 (5). (b) Coordination sphere around the tin atoms. (c) Schematic representation of the planes formed by the Sn(dtc) (OOC) moieties having approximate perpendicular orientation to the macrocycle skeleton plane.

the weaker Sn···O and Sn···S interactions occupy capping positions. When compared to the seven-coordinate tin derivative 1, the Sn−S, Sn···S, and Sn−O bonds are significantly shorter in accordance with the lower coordination number (Table 3). Nevertheless, the Sn···O bond length increases from 2.703(7) to 2.816(3) Å for one of the two crystallographically independent molecules, while it remains practically constant for the other. Within the macrocycle, the planes of the (dtc)Sn(OOC) fragments adopt an almost perpendicular orientation with respect to the macrocycle skeleton, which orients half the n-butyl groups toward the macrocycle cavity (Figure 3c). The intramolecular Sn···Sn

dimension, the crystal structure is stabilized additionally by intermolecular C−H···O, C−H···S, and C−H···π interactions (Table S1, Supporting Information). In the case of compound [nBu2Sn(L5-Bn)]2 (5), the expected dinuclear 22-membered macrocyclic structure crystallized in form of two crystallographically independent molecules (5A and 5B, Figure 3a). The ligand functions are bound in an anisobidentate coordination mode to two different tin atoms, generating a six-coordinate skewed-trapezoidal bipyramidal coordination environment, in which the organic groups occupy the axial positions (Figure 3b). Alternatively, the coordination polyhedron can be described as bicapped tetrahedral, in which H


Article

Inorganic Chemistry

Figure 4. (a) Perspective view of the molecular structure for compound [Ph2Sn(L7-iPen)]2 (12). (b) Coordination sphere around the tin atoms. (c) Schematic representation of the planes formed by the Sn(dtc) (OOC) moieties having approximate perpendicular orientation to the macrocycle skeleton plane.

distances are 6.84 and 6.69 Å for 5A and 5B, respectively. In the pentylene spacer, the CH2−CH2−CH2−CH2 entities have torsion angles in the range of 178.0(2)−179.6(2)°, but contrary to compound 1, the CH2−CH2−CH2−X segments containing the metal-coordinating dithiocarbamate and carboxylate functions exhibit now both torsion angles close to 60°, that is, −65.5(3) and −66.0(3)° for CH2−CH2−CH2−COO; 66.0(3) and 62.1(3)° for CH2−CH2−CH2−Ndtc. Additionally, in this case the mean planes of the dtc and carboxylate functions in each ligand are almost parallel to each other (8.5°), giving a ligand topology ideal for macrocyclization. The crystal structure is further stabilized through a number of C−H···O interactions with the carboxylate oxygen atoms, involving both CH2 and CH hydrogen atoms. Additionally, there is one C−H···S and one C−H···π contact (Figure S80, Table S1, Supporting Information). Compound [Ph2Sn(L7-iPen)]2 (12), wherein the aliphatic spacer consists of seven methylene groups, crystallized also in the form of a macrocyclic structure, in this case with a 26membered ring (Figure 4a). The coordination geometry of the tin atoms is similar to that observed in the crystal structure of compound 5 (Figure 4b and Table 3). As for [nBu2Sn(L5Bn)]2 (5), half the Sn-phenyl groups are oriented toward the cavity formed by the macrocycle. According to the increase of the alkylene spacer, the intramolecular Sn···Sn distance increases from 6.84/6.69 Å for 5A and 5B to 8.15 Å for 12 (Figure 4c). The general aspects of the ligand conformation are similar in both macrocycles 5 and 12; however, there is one significant difference regarding the overall molecular conformation, which is illustrated and discussed in the section of the DFT calculations (vide infra). The crystal structure is stabilized by a series of C−H···O, C− H···S, and C−H···π interactions, which are summarized in Table S1 and shown in Figure S81 (Supporting Information). 3.3. Geometry Optimizations by Density Functional Theory Calculations. Analysis of Odd−Even Effects in the Macrocyclic Structures. The single-crystal X-ray diffraction study revealed interesting characteristics for the molecular

structures of macrocycles [nBu2Sn(L5-Bn)]2 (5) and [Ph2Sn(L7-iPen)]2 (12). Unfortunately, attempts to grow crystals for a larger number of the metal complexes examined herein were not successful. To enable a more systematic examination of the factors relevant for the changes in the molecular structures of 1−18, the geometries of the dimethyltin complexes were optimized by means of quantum mechanical DFT calculations using a combination of the B3LYP functional and the def2TZVP basis set. Previous reports have shown that DFT calculations confidently reproduce the geometries of diorganotin dithiocarbamates obtained from single-crystal X-ray diffraction analysis.13,21,68−71 With the purpose to reduce the computational cost, the benzyl/isopentyl substituents at the Ndtc nitrogen atoms were replaced by methyl groups in all cases, and, in accordance with the single-crystal X-ray diffraction analysis for macrocycles 5 and 12, Ci-symmetry was imposed. For the sake of a comprehensive analysis, the macrocycles having 3, 8, 9, and 12 methylene groups in the spacer between the metal-coordinated carboxylate and dithiocarbamate functions were also included in the computational analysis. Of these, the complexes corresponding to ligands L8, L9, and L12 were not characterized experimentally, since the respective amino acid precursors were commercially not available. On the contrary, the molecular structures of compounds [R2Sn(L3-Bn)]2 (with R = Me, nBu, and Ph) have been reported previously but not examined by theoretical calculations.43 The geometry optimizations of the macrocyclic dimethyltin complexes derived from ligands Lx-Me (with x = 3, 4, ..., 12) revealed that [2 + 2] assemblies are feasible in all cases, including the compound carrying four methylene groups in the aliphatic spacer, which gave a 2D coordination polymer in the solid state (compound 1). Table 4 summarizes some relevant structural parameters for the geometry-optimized structures examined in this section. When compared to the X-ray structures of compounds [Me2Sn(L3-Bn)]2,43 [nBu2Sn(L5Bn]2 (5), and [Ph2Sn(L7-iPen)]2 (12), the geometric parameters computed for the structural analogues [Me2SnI


J

2.504 2.493(1) 2.517 2.530(2) 2.513 2.514 2.4743(7) 2.4813(7) 2.506 2.514 2.518 2.4928(9) 2.509 2.514 2.519 2.510 2.515 2.519 2.512

2.851 2.734(1) 2.873 2.804(2) 2.890 2.859 2.7482(8) 2.7563(8) 2.888 2.889 2.879 2.7509(9) 2.900 2.896 2.886 2.903 2.900 2.889 2.907

Sn···S2 2.146 2.135(2) 2.153 2.169(6) 2.138 2.135 2.142(2) 2.154(2) 2.117 2.136 2.138 2.167(2) 2.119 2.135 2.136 2.120 2.136 2.135 2.122

Sn−O1 2.959 2.924(2) 2.764 2.703(7) 2.827 2.936 2.816(3) 2.708(3) 3.004 2.817 2.811 2.748(2) 2.941 2.803 2.803 2.914 2.783 2.805 2.882

Sn···O2 1.336 1.327(4) 1.337 1.348(11) 1.338 1.338 1.324(4) 1.326(4) 1.337 1.339 1.339 1.323(4) 1.338 1.339 1.340 1.338 1.339 1.340 1.338

N−CS2 7.68 7.79 7.90 8.35 9.32 8.34 8.42 8.54 8.40 9.54 9.10 8.70 8.49 9.69 9.42 8.60 9.90 9.84

7.31 6.42 6.84 6.69 11.00 9.44 8.31 8.15 13.38 11.67 10.66 15.76 13.98 13.06 18.23

C···Cf

7.18 7.10 8.16

Sn···Sne 82.78 81.18(6) 84.54 82.10(17) 83.44 82.64 81.62(5) 83.04(5) 81.38 83.56 83.52 78.77(7) 81.65 83.61 83.09 81.94 83.54 83.42 82.05

S1−Sn−O1 161.52 162.3(6) 156.97 158.53(16) 159.49 160.92 159.09(5) 155.85(5) 164.17 159.04 158.73 161.16(7) 163.04 158.87 159.23 162.33 158.74 158.93 161.77

S2···Sn···O2 67.19 68.52(2) 66.86 67.40(7) 66.45 66.80 68.65(2) 68.54(2) 66.53 66.48 66.54 68.41(3) 66.36 66.39 66.41 66.31 66.30 66.38 66.24

S1−Sn···S2 48.57 49.1(11) 51.75 52.0(2) 50.81 48.97 50.75(10) 52.70(10) 47.84 50.97 51.05 51.75(10) 48.92 51.19 51.18 49.39 51.51 51.15 49.92

O1−Sn···O2

C−Sn−C 128.98 127.97(14) 132.30 151.9(4) 130.96 128.45 132.35(12) 138.28(11) 127.88 130.67 131.01 135.23(13) 128.69 130.75 130.92 128.98 131.03 131.13 129.46

a Data from ref 43. bData were collected at T = 100 K. cThis work. dTwo crystallographically independent molecules in the asymmetric unit. eTransannular distance between the tin atoms within the macrocycle. fShortest transannular distance between the carbon atoms in the central region of the macrocycle ring.

[Me2SnL6-Me]2 ac-[Me2SnL7-Me]2 sp-[Me2SnL7-Me]2 sp-[Ph2SnL7-iPen]2 (X-ray)b,c [Me2SnL8-Me]2 ac-[Me2SnL9-Me]2 sp-[Me2SnL9-Me]2 [Me2SnL10-Me]2 ac-[Me2SnL11-Me]2 sp-[Me2SnL11-Me]2 [Me2SnL12-Me]2

[Me2SnL3-Me]2 [Me2SnL3-Bn]2 (X-ray)a,b [Me2SnL4-Me]2 [Me2SnL4-Bn]2 (X-ray)b,c ac-[Me2SnL5-Me]2 sp-[Me2SnL5-Me]2 ac-[nBu2SnL5-Bn]2 (X-ray)b,c,d

Sn−S1

Table 4. Selected Bond Distances (Å), Bond Angles (deg), and Intramolecular Distances (Å) for the B3LYP/def2-TZVP Geometry-Optimized Molecular Structures of Compounds [Me2SnLx-Me]2 with x = 3−12

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Figure 5. B3LYP/def2-TZVP geometry-optimized structures for macrocycles [Me2Sn(Lx-Me)]2 (x = 3−12), showing (a) the even-series and (b, c) the ac- and sp-conformers of the odd-series. Note: The C···C distances correspond to the shortest transannular distances between the carbon atoms in the central region of the macrocycle ring.

orientation with respect to the macrocycle plane (Figure 5a). Starting from [Me2Sn(L4-Me)]2, the intramolecular Sn···Sn distance increases in average by 2.52 Å per ethylene group (Figures 5a and 6a). The curvature of the ligands can be quantified by measuring the transannular C···C distance in the central section of the macrocycle, which shows a continuous increase of ∼0.49 Å per additional ethylene group (Figures 5a and 6b). In the even series, the Sn···O and Sn···S bonds are significantly larger than the Sn−O and Sn−S bonds (Δd = 0.61−0.89 Å for Sn−O/Sn···O; Δd = 0.36−0.40 Å for Sn−S/ Sn···S) and constitute the outer rim of the macrocycle structure. The resulting trapezoidal shape of the SnS2O2 coordination environment generates an angular (dtc)Sn(OOC) building block, which together with the curved ligands enables macrocyclization as illustrated in Scheme 3a. At first sight this seems to be unusual, since with exception of [Me2Sn(L4-Me)]2

(L3-Me)]2, [Me2Sn(L5-Me)]2, and [Me2Sn(L7-Me)]2 are in good agreement. Moreover, there is even a close relationship between the coordination geometries of the tin atoms in macrocyclic [Me2Sn(L4-Me)]2 and the experimentally determined polymeric structure of [Me2Sn(L4-Bn)]n (1), indicating that this derivative is probably propense to supramolecular isomerism,72 as previously observed for a diorganotin dicarboxylate exhibiting both a tetrameric and a polymeric structure.67 The most important finding of the computational analysis was the observation that the conformation and shape of the [2 + 2] macrocyclic assemblies are strongly dependent on the odd−even character of the aliphatic spacer between the metalcoordinated functions. Macrocycles of composition [Me2Sn(Lx-Me)]2 with an even number of methylene groups (x = 4, 6, 8, 10, and 12) have approximate elliptic shape with the organic substituents attached to the tin atoms having perpendicular K


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the torsion angles of the −(CH2)x− chains and the CH2− CH2−CH2−X segments in the Ndtc(Me) (CH2)xCOO (x = 6, 8, 10, and 12) ligands are all close to 180° (Table 5). However, because of the sp2-hybridization of the nitrogen atom the CSS group disrupts the ligand linearity, as illustrated by the CSS−N− CH2−CH2 torsion angles in the range from −90.4 to −92.7° for [Me2Sn(Lx-Me)]2 with x = 6, 8, 10, and 12 (Table 5). Together with the deviation of the CH2−CH2−CH2−CH2, Ndtc−CH2−CH2−CH2, and CH2−CH2−CH2−COO torsion angles from the ideal value of 180°, the overall curved ligand shape is generated (Figure 5a). A further interesting aspect is that the metal-coordinating carboxylate and dtc functions are almost parallel to each other, as indicated by the angle formed between the corresponding mean planes, that is, 2.5−3.8° for [Me2Sn(Lx-Me)]2 with x = 6, 8, 10, and 12. When viewed perpendicular to the −(CH2)x− chains, the macrocycles exhibit a crown-type all chair-conformation (Figure S82, Supporting Information). Although at first sight the overall shape of the macrocycles containing an odd number of methylene groups is similar to that found for the even series of complexes (Figure 5b,c), there are significant differences, which explain the large variations in the transannular Sn···Sn and C···C distances. For [Me2Sn(LxMe)]2 with x = 5, 7, 9, and 11, the transannular Sn···Sn separation increases by ∼2.2 Å for each ethylene group, which is significantly less than for the even series. The −(CH2)x− chains have torsion angles with values similar to those found for the even series, but the CH2−CH2−CH2−X (X = Ndtc, Ccarboxylate) segments exhibit now torsion angles close to 60° (Table 5). Considering that the Ndtc−CH2−CH2−CH2 and CH2−CH2−CH2−COO torsion angles can have the same or opposite signs, two stereoconformers arise from the two different options for the mutual spatial orientation of the carboxylate and dtc groups along the CH2···CH2 ligand axis. According to the values for the Ndtc−CH2···CH2−COO torsion angles, the isomers are labeled in what follows anticlinal (ac) and synperiplanar (sp) as established by the Klyne−Prelog nomenclature (see IUPAC Gold Book). In the sp-conformation, the carboxylate and dtc groups are eclipsed when viewed along the CH2···CH2 axis, that is, the Ndtc−CH2···CH2−COO torsion angles are in the range from −7.7 to −12.9°. In the acisomers, the Ndtc−CH2···CH2−COO torsion angles are in the range from 116.6 to 117.8° (Table 5). A summary of the common and distinctive characteristics of the ligand conformations in ac- and sp-[Me2Sn(Lx-Me)]2 (with x = 5, 7, 9, and 11) is given in Table 6. The differences in the molecular shapes in dependence of the variation in the ligand stereochemistry are illustrated by the ligand perspectives and Newman projections given for ac-[Me2Sn(L5-Me)]2 and sp[Me2Sn(L11-Me)]2 in Figure 7. Despite the significant differences found for the ligand and molecular conformations of ac-[Me2Sn(Lx-Me)]2 and sp-[Me2Sn(Lx-Me)]2 with x = 5, 7, 9, and 11, interestingly the bite angle formed between the metal-coordinating carboxylate and dtc functions is almost identical for the ac- and sp-isomers (Figure 7d; Figures S83 and S84, Supporting Information). When comparing the ac- and sp-stereoconformers, the former exhibit a larger transannular Sn···Sn but a smaller C··· C distance (Figures 5b,c and 6). Although to a much smaller extent, similar to the even series there is a tendency to curvature, as illustrated by the C···C distances, which increase by ∼0.19 Å per additional ethylene group for the sp-isomers and 0.08 Å for the ac-isomers (Figure 6b).

Figure 6. Graphics showing the increase of the transannular Sn···Sn (a) and C···C (b) distances in the geometry-optimized structures of macrocycles [Me2Sn(Lx-Me)]2 with x = 3−12) in dependence of an increasing number of methylene groups within the aliphatic spacer. Note: The C···C distances correspond to the shortest transannular distances between the carbon atoms in the central region of the macrocycle ring.

Scheme 3. Schematic Representation Illustrating the Differences in the Assembly of the Carboxylate-dtc Ligand and (dtc)Sn(OOC) Tectons between the Even Series (a) and the Odd Series (b) of [Me2Sn(Lx-Me)]2 with x = 4−12, Giving Rise to Different Shapes of the Macrocyclic Structures

L


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Table 5. Analysis of the Conformational Strain on the Basis of Characteristic Torsion Angles (deg) in the Even and Odd Series of [Me2Sn(Lx-Me)]2 with x = 5 to 12

even series [Me2Sn(L6-Me)]2 [Me2Sn(L8-Me)]2 [Me2Sn(L10-Me)]2 [Me2Sn(L12-Me)]2 odd series ac-[Me2Sn(L5-Me)]2 ac-[Me2Sn(L7-Me)]2 ac-[Me2Sn(L9-Me)]2 ac-[Me2Sn(L11-Me)]2 odd series sp-[Me2Sn(L5-Me)]2 sp-[Me2Sn(L9-Me)]2 sp-[Me2Sn(L9-Me)]2 sp-[Me2Sn(L11-Me)]2 a

CH2−CH2−CH2−CH2

Ndtc−CH2− CH2−CH2

CH2−CH2− CH2−COO

CSS−N−C H2−CH2

Ndtc−CH2···CH2−COOa

178.9, 160.9, −179.6 178.9, 165.0, −179.5, 165.7, −178.6 178.9, 168.6, −179.9, 167.8, −179.0, 167.8, −178.2 179.3, 169.9, −179.7, 169.8, −179.1, 170.3, −178.8, 169.6, −178.6

163.9 167.4 169.1 170.9

162.8 166.3 169.7 171.0

−90.4 −91.4 −91.3 −92.7

109.5 103.1 100.4 97.0

−179.5, −178.9 179.3, −178.7, −179.8, −179.6 179.4, −178.8, −179.9, −178.9, 180.0, −179.2 178.4, −179.3, 179.6, −179.2, 180.0, −179.1, −179.7, −179.6

64.2 65.5 63.7 64.7

68.9 68.3 67.9 68.2

−107.8 −109.2 −109.7 −109.1

117.8 117.2 117.1 116.6

175.6, 179.0 177.1, −178.5, 176.7, −178.9 177.7, −179.1, 177.7, −178.8, 177.8, −179.5 178.9, −179.5, 178.1, −179.0, 177.4, −178.3, 177.1, −178.6

59.3 61.5 61.8 62.2

−69.6 −67.1 −66.9 −67.9

−110.2 −109.8 −109.8 −109.8

−12.9 −7.7 −8.0 −7.8

This virtual torsion angle exhibits the mutual orientation of the metal-coordinating carboxylate and dtc functions.

imately linear building block, which is accomplished by a square-bracket shaped ligand tecton as illustrated in Scheme 3b. A more profound analysis indicates that (dtc)Sn(OOC), but also (dtc)Sn(dtc) and (COO)Sn(OOC) moieties, are versatile building blocks for metalla-supramolecular self-assembly. This is first because diorganotin complexes with the CCOO/dtc···Sn··· CCOO/dtc unit can have either trans or cis configuration, and second, because due to the anisobidentate coordination of the carboxylate and dithiocarbamate groups, the Sn···O and Sn···S distances vary over a broad range. According to a search of the Cambridge Structural Database (CSD; version 5.37, Nov 2015),73 for diorganotin complexes containing the CCOO/dtc··· Sn···CCOO/dtc unit in the trans configuration, the weaker secondary Sn···O and Sn···S interactions vary from 2.39 to 2.92 Å for the Sn−carboxylate and from 2.74 to 3.11 Å for the Sn−dithiocarbamate groups. Taking into account also the variations of the Sn−O and Sn−S bond lengths in the ranges of 2.06−2.18 and 2.46−2.57 Å, respectively, the CCOO/dtc···Sn··· CCOO/dtc angles span an overall range of 130−163°. For the less common cis complexes, which are mainly observed for diphenyltin dithiocarbamates,11,13,21 the corresponding Sn−S and Sn···S bond distances are in the ranges of 2.54−2.61 and 2.62−2.95 Å, giving CCOO/dtc···Sn···CCOO/dtc angles varying from 98 to 118°. Scheme 4 illustrates the specific ranges found in the CSD for the Sn−X and Sn···X (X = O, S) bond distances and CCOO/dtc···Sn···CCOO/dtc angles for each trans-R2Sn(COO)2, trans-R2Sn(COO)(CSS), trans-R2Sn(CSS)2, and cis-R2Sn(CSS)2. Analysis of Small Macrocycles. For the complex having a propylene spacer, that is, [Me2SnL3-Me]2, the conformation of the macrocyclic ring is different from the remaining members of the odd series (with L5-Me, L7-Me, L9-Me, and L11-Me). This is observed also experimentally, and despite the different substituents at the tin atoms the molecular conformations found in the X-ray structure of [Me2Sn(L3-Bn)]2, [nBu2Sn(L3Bn)]2, and [Ph2Sn(L3-Bn)]2 are similar (Table 4). Because of the smaller ligand extension between the metal centers, the Ndtc−CH2−CH2−CH2 torsion angles have now values of ∼180°, while the CH2−CH2−CH2−COO torsion angles remain

Table 6. Comparison of the Ligand Conformations in acand sp-[Me2Sn(Lx-Me)]2 with x = 5, 7, 9, and 11 CH2−CH2−CH2−CH2 Ndtc−CH2−CH2−CH2 CH2−CH2−CH2−COO Ndtc−CH2···CH2−COO

ac-isomera

sp-isomerb

all-anti gauche (+)-gauchec anticlinal

all-anti gauche (−)-gauchec synperiplanar

a

ac = anticlinal. bsp = synperiplanar. cThe (+) and (−) signs are used to distinguish between positive and negative torsion angles (see Table 5).

The energy differences between the ac- and sp-isomers of the odd series are small, ranging from 0.45 to 0.95 kcal/mol for [Me2Sn(Lx-Me)]2 with x = 5, 7, 9, and 11, which indicates similar thermodynamic stability (Table 7). An important additional difference to the even series is that in both stereoconformers the organic substituents attached to the tin atoms are now parallel instead of perpendicular to the macrocycle plane (Figure 5), which is found also experimentally in the crystal structures of [nBu2Sn(L5-Bn)]2 (5) and [Ph2Sn(L7-iPen]2 (12). The approximate perpendicular orientation of the metal-coordinating carboxylate and dtc functions with respect to the CH2···CH2 axis provides the ligand with a square-bracket shape that is distorted by an angle of ∼120° in the ac-isomer (Figure 7d). For the two crystallographically independent molecules in the asymmetric unit of [nBu2Sn(L5-Bn)]2 (5) the ac-stereoconformer was experimentally observed, while the crystal structure of [Ph2Sn(L7-iPen)]2 (12) exhibited the sp-derivative. Comparative overviews of the experimental and calculated molecular structures for the anticlinal and synperiplanar stereoconformers of [Me2Sn(L5-Me)]2 and [nBu2Sn(L5-Bn)]2 as well as [Me2Sn(L7-Me)]2 and [Ph2Sn(L7-iPen)]2 are given in Figures S83 and S84 (Supporting Information). Analysis of Tecton Characteristics. Because of the perpendicular orientation of the (dtc)Sn(OOC) units with respect to the macrocycle ring plane in the odd series, from this perspective the metal complex constitutes now an approxM


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Figure 7. Perspective views (a, b) and Newman projections (c) illustrating the ligand conformations for the ac- and sp-isomers of [Me2Sn(L5-Me)]2 and [Me2Sn(L11-Me)]2. (d) Perspective views showing the differences in the ligand and macrocycle conformation of ac- and sp-[Me2Sn(L5-Me)]2..

A second important difference arises from the orientation of the organic substituents attached to the tin atoms, which is approximately perpendicular to the macrocycle ring plane in [Me2SnL3-Me]2 but parallel for the remaining complexes of the odd series (compare Figure 5b,c and Figure 8). Despite these differences, for [Me2Sn(L3-Me)]2 the angle formed between the mean planes of the carboxylate and dtc groups is 5.4°, which is comparable to the values of 11.9, 7.1, 5.2, and 7.7° for the complexes (ac-isomers) derived from L5-Me, L7-Me, L9Me, and L11-Me, indicating an approximate parallel orientation of the metal-coordinating functions. A somewhat similar situation arises for the macrocycle derived from ligand L4-Me, when compared to the analogues of L6-Me, L8-Me, L10-Me, and L12-Me. For [Me2Sn(L4-Me)]2, the CH2−CH2−CH2−CH2 and Ndtc−CH2−CH2−CH2 segments have torsion angles with values of 171.7 and 164.1°, respectively, which are similar to those found for [Me2Sn(Lx-

Table 7. Relative Energies (kcal/mol) between the Geometry-Optimized ac- and sp-Stereoconformers for Macrocycles [Me2Sn(Lx-Me)]2 Having an Odd Number of Methylene Groups in the Aliphatic Spacer ac-isomera

sp-isomerb

0.00 0.00 0.00 0.00

0.98 0.76 0.45 0.65

[Me2Sn(L5-Me)]2 [Me2Sn(L7-Me)]2 [Me2Sn(L9-Me)]2 [Me2Sn(L11-Me)]2 a

ac = anticlinal. bsp = synperiplanar.

close to 60° (Figure 8). For the geometry-optimized structure of [Me2Sn(L3-Me)]2, the corresponding values are 174.8 and 71.7°, respectively, which are in good agreement with the values determined experimentally for [Me2Sn(L3-Bn)]2, that is, 175.5(4)° for Ndtc−C−C−C and 68.2(4)° for C−C−C−COO. N


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Interestingly, the ligand conformations in macrocyclic [Me2Sn(L4-Me)]2 and polymeric [Me2Sn(L4-Bn)]n (1) have similar values for the Ndtc−C−C−C and C−C−C−COO torsion angles, that is, −164.1 and 88.5° for [Me2SnL4-Me]2 versus −178.3(7) and 68.7(10)° for [Me2Sn(L4-Bn]n, but exhibit a significant difference for the angle formed between the mean planes of the carboxylate and dtc functions, that is, 8.6° for [Me2Sn(L4Me)]2 versus 51.4° for [Me2Sn(L4-Bn)]n, which arises mainly from the rotation of the carboxylate moiety around the C−COO bond (compare Figure 9a,b).

Scheme 4. Range of Sn−X and Sn···X (X = O, S) Bond Distances and CCOO/dtc···Sn···CCOO/dtc Angles for trans- and cis-Diorganotin Complexes with Carboxylate and/or Dithiocarbamate Ligands, According to the Entries Found in the CSD73

Me)]2 with x = 6, 8, 10, and 12 (Table 5). However, the CH2− CH2−CH2−COO entity is gauche for [Me2Sn(L4-Me)]2 but anti for [Me2Sn(Lx-Me)]2 with x = 6, 8, 10 and 12, as seen from the values for the corresponding torsion angles, that is, 88.5° for [Me2Sn(L4-Me)]2 versus 162.8−171.0° for [Me2Sn(Lx-Me)]2 with x = 6, 8, 10, and 12. Nevertheless, similar to the odd series the mutual distortion of the metal-coordinated carboxylate and dtc mean planes is comparable: 8.6° for [Me2SnL4-Me]2 versus 2.5−3.8° for [Me2Sn(Lx-Me)]2 with x = 6, 8, 10, and 12.

Figure 9. Lateral and front views of the ligand conformations in (a) the geometry-optimized macrocyclic structure of [Me2Sn(L4-Me)]2 and (b) the experimentally determined (SXRD) molecular structure of the 2D coordination polymer [Me2Sn(L4-Bn)]n (1).

Figure 8. (a) Perspective views of the experimentally determined (SXRD) molecular structures of compounds [R2Sn(L3-Bn)]2 (with R = Me, nBu, Ph). (b) Perspective view of the geometry-optimized molecular structure of [Me2Sn(L3-Me)]2. (c) Perspective view and Newman projections of the ligand conformation in [Me2Sn(L3-Me)]2. Note: Compound [Ph2Sn(L3-Bn)]2 comprises two crystallographically independent molecules in the asymmetric unit. O


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Figure 10. Geometry-optimized molecular structures of [Me2Sn(L5-Me)]2 with (a) homo-ditopic and (b) hetero-ditopic coordination.

Analysis of Conformational Strain in the Macrocycles. Independently, if the (dtc)Sn(OOC) fragments are oriented parallel (even series) or perpendicular (odd series) to the macrocycle ring plane, the carboxylate and dtc planes are approximately parallel to each other in both the even and the odd series of the [2 + 2] macrocyclic assemblies, and the (dtc)Sn(OOC) units have similar geometries (Scheme 3 and Figure 5). Another interesting observation is that the conformational strain in both the even and the odd series is reduced with increasing macrocyclic ring size. This is illustrated by comparison of the CH2−CH2−CH2−CH2, Ndtc−CH2− CH2−CH2, and CH2−CH2−CH2−COO torsion angles (Table 5). For the even series the torsion angles approach closer to the ideal value of 180° with increasing x. For the odd series, only the CH2−CH2−CH2−CH2 segments have torsion angles close to 180° and, albeit the phenomenon is not as clear as for the even series, there is a clear tendency in the same direction. On the contrary, the torsion angles for Ndtc−CH2−CH2−CH2 and CH2−CH2−CH2−COO with values close to 60° remain rather constant. For the torsion of the dtc function with respect to the aliphatic chain (CSS−N−CH2−CH2), the values are rather constant and approximate −90° for the even series and −110° for the odd series. The listing of torsion angles in Table 5 indicates that the anti conformation is dominant in the aliphatic spacer groups, which, however, are conformationally flexible. In the even series, the curved ligand shape required for macrocyclization is achieved by the spatial orientation of the dtc group due to the sp2 hybridization of the nitrogen atom and the deviations of the Ndtc−CH2−CH2−CH2, CH2−CH2−CH2−COO and some of the CH2−CH2−CH2−CH2 torsion angles from the ideal 180° value (Table 5). On the contrary, in the odd series the CH2− CH2−CH2−CH2 torsion angles are practically ideal, and the square-bracket ligand shape is achieved by the anti → gauche transformation of the Ndtc−CH2−CH2−CH2 and CH2−CH2− CH2−COO fragments. Homoditopic Versus Heteroditopic Coordination. As mentioned in the Introduction, the metal-coordinating dtc and carboxylate functions can coordinate either in a homo- or a hetero-ditopic manner (Scheme 1). Since all complexes examined herein experimentally exhibited the hetero-ditopic coordination mode, apparently the mixed coordination is thermodynamically more stable. To shed some light on this phenomenon, the geometry of two representative macrocycles, [Me2Sn(L4-Me)]2 and [Me2Sn(L5-Me)]2, were optimized also for the homo-ditopic option. Calculation of the energy difference between the two isomers in each case originated a difference of 3.70 kcal/mol for [Me2Sn(L4-Me)]2 and 4.43 kcal/mol for [Me2Sn(L5-Me)]2 in favor of the hetero-ditopic version. Although the comparison of the macrocyclic ring

structures for each pair of isomers reveals similar ligand conformations, the overall molecular shapes resulted quite different, giving a trapezoidal form for the homo-ditopic bound isomer and an approximate rectangular shape for the complex with the mixed coordination mode (Figure 10). Comparison of additional geometric parameters showed that the Sn−S and Sn···S bonds in the homo-ditopic complexes were significantly larger than in the hetero-ditopic complexes (2.57/3.03 vs 2.52/ 2.87 Å for [Me2Sn(L4-Me)]2; 2.56/3.04 vs 2.51/2.89 Å for [Me2Sn(L5-Me)]2). However, for the Sn−O/Sn···O bonds the tendency was inverted (2.13/2.55 Å versus 2.15/2.76 Å for [Me2Sn(L4-Me)]2; 2.10/2.66 vs 2.14/2.83 Å for [Me2Sn(L5Me)]2). A further significant difference was observed for the N−C−S−Sn and C−C−O−Sn torsion angles, which should have ideally a value of 180° to allow for an optimum delocalization of the π-electron density within the metalcoordinated COO and dtc groups. The values measured for the hetero-ditopic complexes [Me2Sn(L4-Me)]2 and [Me2Sn(L5Me)]2 were 179.7/175.5° for the N−C−S−Sn and 174.6/ 179.6° for the C−C−O−Sn segments. In the homo-ditopic versions, most of the corresponding values were significantly smaller (167.8/169.7° and 177.6/178.2°), indicating an increased annular ring strain. The larger deviation from the ideal 180° value for the homo-ditopic complex structures can be seen also from the larger curvature of the dtc-Sn-dtc moiety within the macrocyclic ring (Figure 10).

4. CONCLUSIONS This comprehensive experimental and computational study has shown that dinuclear metalla-macrocyclic structures prepared from homologous series of ligands containing aliphatic spacer groups are susceptible to significant variations of the molecular conformation, shape, and cavity size. Aside from the coordination geometry of the metal center, for the purpose of fine-tuning the size and functionality of the cavity in metallasupramolecular assemblies the odd−even effect of the organic connector between the metal-coordinating functions is an important factor than can give rise to different isomers of similar energy but significant structural variations. Although well-known in organic chemistry, these and related phenomena have been little explored so far in coordination-driven selfassembly and are relevant not only for macrocyclic structures but also for cage-type and infinite coordination polymers. The macrocycles examined herein can be converted into molecular receptors by introducing heteroatoms such as oxygen, nitrogen, or sulfur within the aliphatic chains. Moreover, a large number of other metal ions can be employed for the generation of similar homonuclear assemblies, and even heterometallic macrocycles assemblies, but might be easily achieved by the P


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Inorganic Chemistry

(6) Prabusankar, G.; Murugavel, R. Hexameric Organotincarboxylates with Cyclic and Drum Structures. Organometallics 2004, 23, 5644− 5647. (7) Baul, T. S. B.; Singh, K. S.; Lyčka, A.; Holčapek, M.; Linden, A. Synthesis of a Cyclic Dinuclear Organotin Carboxylate via Simultaneous Debenzylation and Decarbonylation Reactions: X-Ray Crystal Structure of [(PhCH2)2{O2CC6H4{N(H)-N = (C6H3-4(=O)5-O)}-o}Sn]2. J. Organomet. Chem. 2005, 690, 1581−1587. (8) Ma, C.; Zhang, Q.; Zhang, R.; Wang. Self-Assembly of Dialkyltin Moieties and Mercaptobenzoic Acid into Macrocyclic Complexes with Hydrophobic ″Pseudo-Cage″ or Double-Cavity Structures: Supramolecular Infrastructures Involving Intermolecular C-H···S Weak Hydrogen Bonds and Pi-Pi Interactions. Chem. - Eur. J. 2006, 12, 420−428. (9) Bowen, R. J.; Caddy, J.; Fernandes, M. A.; Layh, M.; Mamo, M. A.; Meijboom, R. Synthesis and Characterisation of Dialkyltin 2,3Bis(Diphenylphosphino)Maleic Acid Adducts. J. Organomet. Chem. 2006, 691, 717−725. (10) Chandrasekhar, V.; Thirumoorthi, R. 1,1′-Ferrocenedicarboxylate-Bridged Redox-Active Organotin and -tellurium-Containing 16Membered Macrocycles: Synthesis, Structure, and Electrochemistry. Organometallics 2007, 26, 5415−5422. (11) Reyes-Martínez, R.; García y García, P.; López-Cardoso, M.; Höpfl, H.; Tlahuext, H. Self-Assembly of Diphenyltin(IV) and TrisDithiocarbamate Ligands to Racemic Trinuclear cavitands and Capsules. Dalton Trans. 2008, 6624−6627. (12) González-Rivas, N.; Cuevas-Yañez, E.; Barba, V.; Beltran, H. I.; Reyes, H. Rectangular Bimetallic Diorganotin Macrocycle Obtained through a Combination of Metallosupramolecular Chemistry with Imine Bond Formation. Inorg. Chem. Commun. 2013, 37, 110−113. (13) Celis, N. A.; Villamil-Ramos, R.; Höpfl, H.; Hernández-Ahuactzi, I. F.; Sánchez, M.; Zamudio-Rivera, L. S.; Barba, V. Dinuclear Monomeric and Macrocyclic Organotin Dithiocarbamates Derived from 1,10-Diaza-18-crown-6 and 4,4′-Trimethylenedipiperidine. Eur. J. Inorg. Chem. 2013, 2013, 2912−2922. (14) Garcia-Zarracino, R.; Ramos-Quiñones, J.; Höpfl, H. SelfAssembly of Dialkyltin(IV) Moieties and Aromatic Dicarboxylates to Complexes with a Polymeric or a Discrete Trinuclear Macrocyclic Structure in the Solid State and a Mixture of Fast Interchanging Cyclooligomeric Structures in Solution. Inorg. Chem. 2003, 42, 3835− 3845. (15) Yin, H.-D.; Hong, M.; Yang, M.-L.; Cui, J.-C. Cyclotrimeric and Weakly-Bridged Cyclotetrameric Organotin(IV) Compounds Assembled from 5-Hydroxyisophthalic Acid: Synthesis and Structural Characterization. J. Mol. Struct. 2010, 984, 383−388. (16) Li, W.; Du, D.; Liu, S.; Zhu, C.; Sakho, A. M.; Zhu, D.; Xu, L. Self-Assembly of a Novel 2D Network Polymer: Syntheses, Characterization, Crystal Structure and Properties of a Four-Tin-Nuclear 36Membered Diorganotin(IV) Macrocyclic Carboxylate. J. Organomet. Chem. 2010, 695, 2153−2159. (17) Garcia-Zarracino, R.; Höpfl, H. Self-Assembly of Diorganotin(IV) Oxides (R = Me, nBu, Ph) and 2,5-Pyridinedicarboxylic Acid to Polymeric and Trinuclear Macrocyclic Hybrids with Porous SolidState Structures: Influence of Substituents and Solvent on the Supramolecular Structure. J. Am. Chem. Soc. 2005, 127, 3120−3130. (18) Yin, H. D.; Li, F. H.; Wang, C.-H. Syntheses, Characterization And Crystal Structure of Diorganotin and Triorganotin Heterocyclicdicarboxylates with Monomeric, 2D Network and 3D Framework Structures. Inorg. Chim. Acta 2007, 360, 2797−2808. (19) Torres-Huerta, A.; Rodríguez-Molina, B.; Höpfl, H.; GarcíaGaribay, M. A. Synthesis and Solid-State Characterization of SelfAssembled Macrocyclic Molecular Rotors of Bis(dithiocarbamate) Ligands with Diorganotin(IV). Organometallics 2014, 33, 354−362. (20) Hernández-Ahuactzi, I. F.; Cruz-Huerta, J.; Tlahuext, H.; Barba, V.; Guerrero-Alvarez, J.; Höpfl, H. Tuning the Supramolecular Structure through Variation of the Ligand Geometry and Metal Substituents−Diorganotin Macrocycles and Coordination Polymers Derived from cis- and trans-1,2-, 1,3-, and 1,4-Cyclohexanedicarboxylic

hetero-ditopic dithiocarbamate−carboxylate ligands explored herein, of which the latter are still little explored.74

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b02387. Figures with NMR spectra and experimental HR-MS isotope profiles. Perspective views of the supramolecular interactions in the crystal structures of compounds [Me2Sn(L4-Bn)]n (1), [nBu2Sn(L5-Bn)]2 (5), and [Ph2Sn(L7-iPen)]2 (12). Perspective view of a representative member of the even series, showing the crowntype all chair-conformation. Figures illustrating differences in the molecular structures and ligand conformations for selected calculated and experimental compounds. Table with geometric data for the intermolecular interactions in the crystal structures of compounds [Me2Sn(L4-Bn)]n (1), [nBu2Sn(L5-Bn)]2 (5), and [Ph2Sn(L7-iPen)]2 (12) (PDF) X-ray crystallographic information (CIF) X-ray crystallographic information (CIF) X-ray crystallographic information (CIF)

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AUTHOR INFORMATION

Corresponding Author

*Phone, Fax: +52 777 3297997. E-mail: hhopfl@uaem.mx. ORCID

Herbert Höpfl: 0000-0002-4027-0131 Notes

The authors declare no competing financial interest. Copies of the X-ray crystallographic data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K. (fax: (+44)1223−336−033; e-mail: deposit@ ccdc.cam.ac.uk; online: http://www.ccdc.cam.ac.uk).

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ACKNOWLEDGMENTS Financial support from Consejo Nacional de Ciencia y Tecnologiá (CONACyT) through Project Nos. 158098 and 229929 is gratefully acknowledged. The authors acknowledge access to Laboratorio Nacional de Estructura de Macromoléculas (LANEM). The authors thank I. Q. Geiser Cuéllar Rivera and M. C. Maria Eugenia Ochoa Becerra for assistance in processing the mass spectrometric data.

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REFERENCES

(1) Yoshizawa, M.; Klosterman, J. K.; Fujita, M. Functional Molecular Flasks: New Properties and Reactions within Discrete, Self-Assembled Hosts. Angew. Chem., Int. Ed. 2009, 48, 3418−3438. (2) Cook, T. R.; Stang, P. J. Recent Developments in the Preparation and Chemistry of Metallacycles and Metallacages via Coordination. Chem. Rev. 2015, 115, 7001−7045. (3) Jones, C. J. Transition Metals as Structural Components in the Construction of Molecular Containers. Chem. Soc. Rev. 1998, 27, 289− 300. (4) Breiner, B.; Clegg, J. K.; Nitschke, J. R. Reactivity Modulation in Container Molecules. Chem. Sci. 2011, 2, 51−56. (5) Ma, C.; Han, Y.; Zhang, R.; Wang, D. Self-Assembly of Diorganotin(IV) Moieties and 2-Pyrazinecarboxylic Acid: Syntheses, Characterizations and Crystal Structures of Monomeric, Polymeric or Trinuclear Macrocyclic Compounds. Dalton Trans. 2004, 1832−1840. Q


Article

Inorganic Chemistry and cis,cis-1,3,5-Cyclohexanetricarboxylic Acid. Cryst. Growth Des. 2015, 15, 829−847. (21) Vasquez-Ríos, M. G.; Reyes-Márquez, V.; Höpfl, H.; TorresHuerta, A.; Guerrero-Á lvarez, J.; Sánchez, M.; Hernández-Ahuactzi, I. F.; Ochoa-Lara, K.; Jiménez-Sánchez, A.; Santillán, R. 23- and 27Membered Macrocyclic Diorganotin(IV) Bis-dithiocarbamates: Synthesis, Spectroscopic Characterization, DFT Calculations, and Physicochemical Analysis as Anion Receptors. Eur. J. Inorg. Chem. 2016, 2016, 3429−3440. (22) Nath, M.; Saini, P. K. Chemistry and Applications of Organotin(IV) Complexes of Schiff Bases. Dalton Trans. 2011, 40, 7077−7121. (23) Basu Baul, T. S.; Dutta, D.; De Vos, D.; Höpfl, H.; Singh, P. P.; et al. Advancement towards Tin-based Anticancer Chemotherapeutics: Structural Modification and Computer Modeling Approach to DrugEnzyme Interactions. Curr. Top. Med. Chem. 2013, 12, 2810−2826. (24) Hong, M.; Yin, H.; Zhang, X.; Li, C.; Yue, C.; Cheng, S. Di- and Tri-Organotin(IV) Complexes with 2-Hydroxy-1-Naphthaldehyde 5Chloro-2-Hydroxybenzoylhydrazone: Synthesis, Characterization and in vitro Antitumor Activities. J. Organomet. Chem. 2013, 724, 23−31. (25) Gupta, A. N.; Kumar, V.; Singh, V.; Rajput, A.; Prasad, L. B.; Drew, M. G. B.; Singh, N. Influence of Functionalities on the Structure and Luminescent Properties of Organotin(IV) Dithiocarbamate Complexes. J. Organomet. Chem. 2015, 787, 65−72. (26) Chans, G. M.; Muñoz-Hurtado, J.; Hernández-Ortega, S.; Ramírez-Apan, T.; Nieto-Camacho, A.; Gómez, E. Synthesis and Biological Activity of Trinuclear Seven-Coordinated Tin(IV) Complexes Derived from Tridentate Ligands and Trimesic Acid. J. Coord. Chem. 2015, 68, 3741−3758. (27) Sirajuddin, M.; Ali, S.; Tahir, M. N. Pharmacological Investigation of Mono-, Di- and Tri-Organotin(IV) Derivatives of Carbodithioates: Design, Spectroscopic Characterization, Interaction With SS-DNA and POM Analyses. Inorg. Chim. Acta 2016, 439, 145− 158. (28) Heard, P. J. Main Group Dithiocarbamate Complexes. Prog. Inorg. Chem. 2005, 53, 1−70. (29) Sedaghat, T.; Goodarzi, K. Synthesis and Characterization of New Diorganotin(IV) Complexes with Dithiocarbamate Derivative of Glycine. Phosphorus, Sulfur Silicon Relat. Elem. 2007, 182, 2227−2233. (30) Pellerito, L.; Nagy, L. Organotin(IV)n+ Complexes formed with Biologically Active Ligands: Equilibrium and Structural Studies, and Some Biological Aspects. Coord. Chem. Rev. 2002, 224, 111−150. (31) Ronconi, L.; Marzano, C.; Russo, U.; Sitran, S.; Graziani, R.; Fregona, D. Synthesis, Characterization and in vitro Cytotoxicity of New Organotin(IV) Derivatives of N-Methylglycine. J. Inorg. Biochem. 2002, 91, 413−420. (32) Nath, M.; Pokharia, S.; Eng, G.; Song, X.; Kumar, A. Comparative Study of Structure−Activity Relationship of Di- and Tri-Organotin(IV) Derivatives of Amino Acid and Peptides. J. Organomet. Chem. 2003, 669, 109−123. (33) Eddaoudi, M.; Kim, J.; Rosi, N.; Vodak, D.; Wachter, J.; O’Keeffe, M.; Yaghi, O. M. Systematic Design of Pore Size and Functionality in Isoreticular MOFs and Their Application in Methane Storage. Science 2002, 295, 469−472. (34) Cookson, J.; Evans, E. A. L.; Maher, J. P.; Serpell, C. J.; Paul, R. L.; Cowley, A. R.; Drew, M. G. B.; Beer, P. D. Metal-Directed Assembly of Large Dinuclear Copper(II) Dithiocarbamate Macrocyclic Complexes. Inorg. Chim. Acta 2010, 363, 1195−1203. (35) Li, C.-J.; Hu, S.; Li, W.; Lam, C.-K.; Zheng, Y.-Z.; Tong, M.-L. Rational Design and Control of the Dimensions of Channels in ThreeDimensional, Porous Metal-Organic Frameworks Constructed with Predesigned Hexagonal Layers and Pillars. Eur. J. Inorg. Chem. 2006, 2006, 1931−1935. (36) Sudik, A. C.; Côté, A. P.; Wong-Foy, A. G.; O’Keeffe, M.; Yaghi, O. M. A Metal−Organic Framework with a Hierarchical System of Pores and Tetrahedral Building Blocks. Angew. Chem., Int. Ed. 2006, 45, 2528−2533. (37) Hernández-Ahuactzi, I. F.; Höpfl, H.; Barba, V.; Román-Bravo, P.; Zamudio-Rivera, L. S.; Beltrán, H. I. Pore-Size Tuning in Double-

Pillared Metal-Organic Frameworks Containing Cadmium Clusters. Eur. J. Inorg. Chem. 2008, 2008, 2746−2755. (38) Zheng, Y.-R.; Northrop, B. H.; Yang, H.-B.; Zhao, L.; Stang, P. J. Geometry Directed Self-Selection in the Coordination-Driven SelfAssembly of Irregular Supramolecular Polygons. J. Org. Chem. 2009, 74, 3554−3557. (39) Han, Y.-F.; Li, H.; Jin, G.-X. Host−Guest Chemistry with Biand Tetra-Nuclear Macrocyclic Metallasupramolecules. Chem. Commun. 2010, 46, 6879−6890. (40) Kiguchi, M.; Takahashi, T.; Takahashi, Y.; Yamauchi, Y.; Murase, T.; Fujita, M.; Tada, T.; Watanabe, S. Electron Transport through Single Molecules Comprising Aromatic Stacks Enclosed in Self-Assembled Cages. Angew. Chem., Int. Ed. 2011, 50, 5708−5711. (41) Barnes, J. C.; Juríček, M.; Strutt, N. L.; Frasconi, M.; Sampath, S.; Giesener, M. A.; McGrier, P. L.; Bruns, C. J.; Stern, C. L.; Sarjeant, A. A.; Stoddart, J. F. ExBox: A Polycyclic Aromatic Hydrocarbon Scavenger. J. Am. Chem. Soc. 2013, 135, 183−192. (42) Alvariño, C.; Pía, E.; García, M. D.; Blanco, V.; Fernández, A.; Peinador, C.; Quintela, J. M. Dimensional Matching of Polycyclic Aromatics with Rectangular Metallacycles: Insertion Modes Determined by [C-H···π] Interactions. Chem. - Eur. J. 2013, 19, 15329− 15335. (43) Cruz-Huerta, J.; Carillo-Morales, M.; Santacruz-Juárez, E.; Hernández-Ahuactzi, I. F.; Escalante-García, J.; Godoy-Alcantar, C.; Guerrero-Alvarez, J. A.; Höpfl, H.; Morales-Rojas, H.; Sánchez, M. Macrocyclic Diorganotin Complexes of γ-Amino Acid Dithiocarbamates as Hosts for Ion-Pair Recognition. Inorg. Chem. 2008, 47, 9874− 9885. (44) Boese, R.; Weiss, H.-C.; Bläser, D. The Melting Point Alternation in the Short-Chain n-Alkanes: Single-Crystal X-Ray Analyses of Propane at 30 K and of n-Butane to n-Nonane at 90 K. Angew. Chem., Int. Ed. 1999, 38, 988−992. (45) Bond, A. D. On The Crystal Structures and Melting Point Alternation of the N-Alkyl Carboxylic Acids. New J. Chem. 2004, 28, 104−114. (46) Thalladi, V. R.; Nüsse, M.; Boese, R. The Melting Point Alternation in α,ω-Alkanedicarboxylic Acids. J. Am. Chem. Soc. 2000, 122, 9227−9236. (47) Mishra, M. K.; Varughese, S.; Ramamurty, U.; Desiraju, G. R. Odd−Even Effect in the Elastic Modulii of α,ω-Alkanedicarboxylic Acids. J. Am. Chem. Soc. 2013, 135, 8121−8124. (48) Bhattacharya, S.; Saraswatula, V. G.; Saha, B. K. Thermal Expansion in Alkane Diacids-Another Property Showing Alternation in an Odd−Even Series. Cryst. Growth Des. 2013, 13, 3651−3656. (49) Thalladi, V. R.; Boese, R.; Weiss, H.-C. The Melting Point Alternation in α,ω-Alkanediols and α,ω-Alkanediamines: Interplay between Hydrogen Bonding and Hydrophobic Interactions. Angew. Chem., Int. Ed. 2000, 39, 918−922. (50) Thalladi, V. R.; Boese, R.; Weiss, H.-C. The Melting Point Alternation in α,ω-Alkanedithiols. J. Am. Chem. Soc. 2000, 122, 1186− 1190. (51) Mukherjee, G.; Biradha, K. Odd−Even Effects: Diamondoid and Quartz Networks by Bis(pyridylcarboxamido)alkanes Containing Alkyl Chains with an Odd Number of -(CH2)- Groups as Spacers. Cryst. Growth Des. 2011, 11, 924−929. (52) Tothadi, S.; Desiraju, G. R. Synthon Modularity in 4Hydroxybenzamide−Dicarboxylic Acid Cocrystals. Cryst. Growth Des. 2012, 12, 6188−6198. (53) Torres-Huerta, A.; Höpfl, H.; Tlahuext, H.; HernándezAhuactzi, I. F.; Sánchez, M.; Reyes-Martínez, R.; Morales-Morales, D. Dinuclear Macrocyclic Palladium Dithiocarbamates Derived from the Homologous Series of Aliphatic 1,x-Diamines (x = 4−10). Eur. J. Inorg. Chem. 2013, 2013, 61−69. (54) Jelfs, K. E.; Eden, E. G. B.; Culshaw, J. L.; Shakespeare, S.; Pyzer-Knapp, E. O.; Thompson, H. P. G.; Bacsa, J.; Day, G. M.; Adams, D. J.; Cooper, A. I. In silico Design of Supramolecules from Their Precursors: Odd−Even Effects in Cage-Forming Reactions. J. Am. Chem. Soc. 2013, 135, 9307−9310. R


Article

Inorganic Chemistry (55) Borch, R. F. Reductive Amination with Sodium Cyanoborohydride-N,N-Dimethylcyclohexylamine. Org. Synth. 1988, 6, 499. (56) SMART, Bruker Molecular Analysis Research Tool, versions 5.057 and 5.618; Bruker Analytical X-ray Systems Inc: Madison, WI, 1997 and 2000. (57) SAINT+NT, Data Reduction Software, versions 6.01 and 6.04; Bruker Analytical X-ray Systems Inc: Madison, WI, 1999 and 2001. (58) Sheldrick, G. M. Foundations of Crystallography. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008, 64, 112−122. (59) SHELXTL-NT, Crystal Structure Analysis Package, versions 5.10 and 6.10; Bruker Analytical X-ray Systems Inc: Madison, WI, 1999 and 2000. (60) Brandenburg, K. Diamond, Version 3.1c; Crystal Impact GbR: Bonn, Germany, 1997. (61) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö .; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision B.01; Gaussian, Inc: Wallingford, CT, 2009. (62) Becke, A. D. Density-Functional Thermochemistry. III. The Role of Exact Exchange. J. Chem. Phys. 1993, 98, 5648−5652. (63) Lee, C.; Yang, W.; Parr, R. G. Development of the Colle-Salvetti Correlation-Energy Formula into a Functional of the Electron Density. Phys. Rev. B: Condens. Matter Mater. Phys. 1988, 37, 785−789. (64) Weigend, F.; Ahlrichs, R. Balanced Basis Sets of Split Valence, Triple Zeta Valence and Quadruple Zeta Valence Quality for H To Rn: Design and Assessment of Accuracy. Phys. Chem. Chem. Phys. 2005, 7, 3297−3305. (65) Lockhart, T. P.; Manders, W. F. Structure determination by NMR spectroscopy. Dependence of |2J(119Sn,1H)| on the Me-Sn-Me angle in methyltin(IV) compounds. Inorg. Chem. 1986, 25, 892−895. (66) Wrackmeyer, B. 119Sn-NMR Parameters. Annu. Rep. NMR Spectrosc. 1985, 16, 73−186. (67) Hernández-Ahuactzi, I. F.; Cruz-Huerta, J.; Barba, V.; Höpfl, H.; Zamudio-Rivera, L. S.; Beltrán, H. I. Sequence of Metal-Organic Oligomer-Polymer Exchange Equilibria in Solution: Supramolecular Isomerism, Self-Assembly Dynamics and Carboxylate Shift of Di-nbutyltin cis-1,4-Cyclohexanedicarboxylate. Eur. J. Inorg. Chem. 2008, 2008, 1200−1204. (68) Buntine, M. A.; Hall, V. J.; Kosovel, F. J.; Tiekink, E. R. T. Influence of Crystal Packing on Molecular Geometry: A Crystallographic and Theoretical Investigation of Selected Diorganotin Systems. J. Phys. Chem. A 1998, 102, 2472−2482. (69) Naseh, M.; Sedaghat, T.; Tarassoli, A.; Shakerzadeh, E. DFT Studies of ONO Schiff Bases, their Anions and Diorganotin(IV) Complexes: Tautomerism, NBO and AIM Analysis. Comput. Theor. Chem. 2013, 1005, 53−57. (70) Gholivand, K.; Rajabi, M.; Dorosti, N.; Molaei, F. Synthesis, Structural Characterization, Density Functional Theory Calculations and Biological Evaluation of a New Organotin(IV) Complex Containing N-Isonicotinyl-N′,N″-Diaryl Phosphorictriamide as NDonor Ligand. Appl. Organomet. Chem. 2015, 29, 739−745. (71) Kadu, R.; Roy, H.; Singh, V. K. Diphenyltin(IV) Dithiocarbamate Macrocyclic Scaffolds as Potent Apoptosis Inducers for Human Cancer HEP 3B and IMR 32 Cells: Synthesis, Spectral Characterization, Density Functional Theory Study and In Vitro Cytotoxicity. Appl. Organomet. Chem. 2015, 29, 746−755.

(72) Moulton, B.; Zaworotko, M. J. From Molecules to Crystal Engineering: Supramolecular Isomerism and Polymorphism in Network Solids. Chem. Rev. 2001, 101, 1629−1658. (73) Groom, C. R.; Bruno, I. J.; Lightfoot, M. P.; Ward, S. C. The Cambridge Structural Database. Acta Crystallogr., Sect. B: Struct. Sci., Cryst. Eng. Mater. 2016, B72, 171−179. (74) Schouwey, C.; Papmeyer, M.; Scopelliti, R.; Severin, K. A Heterometallic Macrocycle as a Redox-Controlled Molecular Hinge. Dalton Trans. 2015, 44, 2252−2258.

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