Cyclic Dinuclear Organotin Cations Stabilized by Bulky Substituents

Article pubs.acs.org/Organometallics

Cyclic Dinuclear Organotin Cations Stabilized by Bulky Substituents Michael Wagner,† Bernhard Zobel,† Christina Dietz,† Dieter Schollmeyer,‡ and Klaus Jurkschat*,† †

Lehrstuhl für Anorganische Chemie II, Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, 44221 Dortmund, Germany ‡ Institut für Organische Chemie, Johannes-Gutenberg-Universität Mainz, Duesbergweg 10-14, 55099 Mainz, Germany S Supporting Information *

ABSTRACT: The syntheses of sterically congested 2,2-bis(diorganochloridostannyl)propane, Me2C(SnClR2)2 (1; R = CH(SiMe3)2), the related salts [cyclo-{Me2C(SnR2)2X}B(ArF)4] (2, X = Cl; 3, X = OAc; 4, X = OH; ArF = 3,5-(CF3)2C6H3), and the fourmembered-ring cyclo-{Me2C(SnR2)2O} (5) are reported. The compounds have been characterized by elemental and EDX analyses, 1 H, 11B, 13C, 19F, 29Si, and 119Sn NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis.

■

INTRODUCTION Main-group organoelement cations, in combination with appropriate counteranions, have been known for a long time,1 and the essentials of their chemistry have been regularly reviewed.2 Nevertheless, these compounds continue to be a subject of ongoing interest.3 Bicentric Lewis acids covering both homo- and heteronuclear combinations of group 13 to group 16 elements have found fruitful applications, such as in frustrated Lewis acid/base pair chemistry, including hydrogen activation4 as well as halide anion recognition and sensing,5 and catalysis in organic synthesis.6a−c Compounds of this type even hold potential as radiotracers for positron emission tomography (PET).6d Selected examples of popular backbones featuring bicentric Lewis acids are given in Chart 1. Spacer-bridged bicentric Lewis acids have been used to stabilize monocationic species. Such systems developed by Müller and co-workers feature spacer-bridged Si/Ge or Si Lewis acidic sites complexing hydride7 or fluoride3k anion. However,

cationic bicentric Lewis acids containing two tin atoms have been almost unexplored (Chart 2). A few examples of such Chart 2. Compounds Containing Cationic Bicentric Lewis Acids Containing Two Tin Atoms

Chart 1. Randomly Selected Representatives of SpacerBridged Bicentric Lewis Acids compounds are [Sn2{CH(SiMe3)2}4(C8H12)OH]I3 (F),8a [{Sn(tmtaa)}2(μ-CH2)]I2 (G; tmtaa = 6,8,15,17-tetramethyl5,9,14,18-tetraazadibenzo[14]annulene dianion), 8b and [R2SnOH(OTf)(H2O)]2 (R = n-Bu, t-Bu, 2-phenylbutyl; Tf = CF3SO2).8c Attempts to prepare methylene- and oligomethylene-bridged dinuclear triorganotin cations failed. The corresponding compounds [Ph2Sn(CH2)nSnPh2X]OTf (X = OH, Ph2P(O)O; n = 1−3) proved to be ion-paired rather than separated cations and anions.9 This is likely the result of insufficient steric protection provided by the less bulky phenyl Received: September 30, 2015 Published: November 19, 2015 © 2015 American Chemical Society

5602

DOI: 10.1021/acs.organomet.5b00829 Organometallics 2015, 34, 5602−5608

Article

Organometallics

In contrast to its parent compound CH2(SnClPh2)2, which is a coordination polymer in the solid state,12 compound 1 is monomeric. The two crystallographically independent Sn(1) and Sn(2) atoms show strongly distorted tetrahedral environments with angles ranging from 93.56(11)° (C(1)−Sn(2)− Cl(2)) to 135.65(16)° (C(8)−Sn(2)−C(1)). The Sn(1)− Cl(1) and Sn(2)−Cl(2) bond distances of 2.3926(10) and 2.3813(13) Å, respectively, are almost equal and conform to a standard Sn−Cl single bond (2.39 Å).13 Notably, the Cl(1) atom approaches the Sn(2) atom via the tetrahedral face defined by C(1), C(8), and Cl(2), and the Cl(2) atom approaches the Sn(1) via the tetrahedral face defined by C(1), C(7), and Cl(1) at distances of 3.4473(19) and 3.6108(11) Å, respectively. These distances are shorter than the sum of the van der Waals radii of the corresponding atoms (3.92 Å),14 rendering the Sn(1) and Sn(2) atoms [4 + 1]-coordinated. As a result of the steric bulk of the CH(SiMe3)2 substituents, the two organotin moieties are twisted toward each other. The Sn(1)−C(1) (2.199(4) Å) and Sn(2)−C(1) (2.233(4) Å) distances are slightly different and are longer than the four other tin−carbon bonds, ranging between 2.141(5) Å (Sn(2)− C(8)) and 2.190(5) Å (Sn(2)−C(9)). The Sn(1)−C(1)− Sn(2) angle of 109.67(17)° is larger than the corresponding angles in Me2C(SnX2R)2 (X = Cl, 106.28(13)°;5 X = H, 104.91(12)°)6 but smaller than the 113.4(10)° reported for CH2(SnClPh2)2.12 The reaction of compound 1 with NaB(ArF)4 in CH2Cl2 gave the chlorido-bridged salt 2 (Scheme 1) as a colorless, air-stable crystalline material that shows very good solubility in polar organic solvents such as CH2Cl2 and CHCl3. Compound 2 is the first halogen-bridged bicentric organotin cation. Mass spectrometric measurements of ([{Sn(tmtaa)}2(μ-CH2)])I+ 8b point to the fact that such a structure is thermodynamically stable, provided the right counterion is used. An ESI-MS spectrum of compound 2 shows a mass cluster centered at m/z 953.3 being assigned to ([(R2Sn)2{μ-C(CH3)2}(μ-Cl)]+. The second chloride anion in compound 2 is not abstracted even when using an excess of NaBArF4 or AgN(SO2CF3)2. The failure of halide abstraction from different substrates by silver salts is well documented and related to the low nucleophilicity of the corresponding counteranions.15 Compound 2 crystallizes with two discrete cation anion pairs in the asymmetric unit. The geometric parameters of these pairs differ only slightly. Consequently, only one of these is discussed in more detail while the second one is given in Figure S2 in the Supporting Information. The molecular structure is shown in Figure 2, and selected interatomic distances and angles are given in the figure caption. The chloride anion bridges the Sn(1) and Sn(2) centers almost symmetrically at distances of 2.5350(11) (Sn(2)− Cl(1)) and 2.5694(11) Å (Sn(1)−Cl(1)). As expected, the bonding angles around the Cl atoms are close to 90° (83.71(4)/85.82(3)°). As a result of considerable strain in the four-membered ring, the geometry around the tetracoordinated tin atoms is even more distorted than in compound 1, with angles ranging from 81.44(13)° (C(11)−Sn(4)−Cl(2)) to 126.58(18)° (C(7)−Sn(2)−C(1)). The C(1) carbon atom is displaced by 0.46 Å from the plane defined by Sn(1), Cl(1), and Sn(2). In solution compounds 1−3 show a hindered rotation about the Sn−CH bond. Thus, two sets of 1H and 13C NMR resonances are observed for the SiMe3 groups. The 119Sn NMR

substituents and the donor capacity, although poor, of the triflate anion. Herein, we report the sterically highly protected 2,2bis(diorganochloridostannyl)propane (R2ClSn)2CMe2 (R = CH(SiMe3)2) and its reaction with NaB(ArF)4 (ArF = 3,5(CF3)2C6H3), providing the four-membered dinuclear salt cyclo-[Me2C(SnR2)2Cl]B(ArF)4. The latter serves as a starting material for subsequent reactions.

■

RESULTS AND DISCUSSION The reaction of Me2C(SnCl2R)2 (R = CH(SiMe3)2),10 which has recently been employed for the synthesis of the subvalent organotin compound (RSn)4(CMe2)2,11 with LiR gave the 2,2bis(diorganochloridostannyl)propane 1 as a colorless crystalline material that is soluble in all common organic solvents (Scheme 1). Scheme 1. Synthesis of Compounds 1−5

Recrystallization from acetone/CH3CN gave the acetone solvate 1·0.5C3H6O. Its molecular structure is shown in Figure 1, and selected interatomic distances and angles are given in the figure caption.

Figure 1. Molecular structure of the compound 1·0.5C3H6O with 30% probability ellipsoids. Disorder at Sn(2) and of one of the SiMe3 moieties, respectively, and the solvate molecule hydrogen atoms are omitted for clarity. Selected interatomic distances (Å): Sn(1)−C(1) 2.199(4), Sn(1)−C(6) 2.176(4), Sn(1)−C(7) 2.165(4), Sn(1)−Cl(1) 2.3926(10), Sn(1)···Cl(2) 3.6108(11), Sn(2)−Cl(1) 3.4473(19), Sn(2)−C(1) 2.233(4), Sn(2)−C(8) 2.141(5), Sn(2)−C(9) 2.190(5), Sn(2)−Cl(2) 2.3813(13). Selected interatomic angles (deg): C(1)−Sn(2)−Cl(2) 93.56(11), C(1)−Sn(1)−Cl(1) 94.98(11), C(7)−Sn(1)−C(1) 130.89(16), C(8)−Sn(2)−C(1) 135.65(16). 5603


Article

Organometallics

phenyl)borinic acid.18 Reports on silylium ion induced B−C cleavage of the BArF4 anion are known in the literature.19 Compound 2 cleaves ethyl acetate, giving the acetate-bridged salt 3 (Scheme 1). The reaction progress was monitored by 1H NMR spectroscopy. The purity of the ethyl acetate used was checked by 13C NMR spectroscopy (Figure S2 in the Supporting Information) in order to exclude a simple metathesis reaction with acetic acid. Compound 3 is an airstable colorless crystalline material which shows rather high solubility in CHCl3 and ethyl acetate. It crystallizes in the space group P1̅ with two independent cation−anion pairs in the asymmetric unit. Their molecular units differ only slightly. The molecular structure of the cation in 3 is shown in Figure 3. For a view of the complete asymmetric unit see Figures S3−S5 in the Supporting Information.

Figure 2. Molecular structure of compound 2 with 30% probability ellipsoids. The second molecule, the anion, and the hydrogen atoms are omitted for clarity. Selected interatomic distances (Å): Sn(1)− C(1) 2.214(4), Sn(1)−C(4) 2.153(4), Sn(1)−C(5) 2.155(5), Sn(1)− Cl(1) 2.5694(11), Sn(2)−C(1) 2.228(4), Sn(2)−C(6) 2.155(5), Sn(2)−C(7) 2.165(5), Sn(2)−Cl(1) 2.5350(11). Selected interatomic angles (deg): C(1)−Sn(1)−C(4) 116.52(17), C(1)−Sn(1)−C(5) 125.06(17), C(1)−Sn(1)−Cl(1) 83.82(11), C(4)−Sn(1)−C(5) 115.50(18), C(4)−Sn(1)−Cl(1) 104.06(12), C(5)−Sn(1)−Cl(1) 99.78(13), C(1)−Sn(2)−C(6) 109.23(18), C(1)−Sn(2)−C(7) 126.58(18), C(1)−Sn(2)−Cl(1) 84.36(11), C(6)−Sn(2)−C(7) 118.38(18), C(6)−Sn(2)−Cl(1) 104.03(12), C(7)−Sn(2)−Cl(1) 105.17(13), Sn(1)−C(1)−Sn(2) 102.95(17), Sn(1)−Cl(1)−Sn(2) 85.82(3).

chemical shift of compound 2 is observed at δ 347 ppm (s, 2 119 J( Sn−117Sn) = 252 Hz). The 1H NMR chemical shift difference of the H-3 proton in croton aldehyde (Childs method)16 is 0.14 ppm on complexation, which equals ca. 15% of the Lewis acidity in SnCl4. This implies that the Lewis acidity of compound 2 is rather low. A solution of compound 2 in CD2Cl2 does not react with elemental hydrogen. However, the addition of a Lewis base (PCy3 (Cy = cyclohexyl) or tmp (tmp = tetramethylpiperidine)) to a solution of compound 2 in CD2Cl2 that had been covered with a hydrogen atmosphere and that had contact to atmospheric moisture gave a 1:1 mixture of compound 1 (δ119Sn 119 ppm) and the neutral oxygen-containing four-membered ring 5 (δ119Sn 158 ppm). Additionally, the protonated bases HPCy3+ (δ31P 35.1 ppm, δ1H 5.00 ppm (d, 1J(1H−31P) = 440 Hz)) and H-tmp+ were observed. Solutions of compound 2 exposed to humid air or in wet solvents decompose within hours or days with partial decomposition of the anion. Partial hydrolysis of the cation in solution over time is evident in the ESI MS spectra, showing the OH-bridged cation of compound 4 at m/z 933.4 (Scheme 1). A compound featuring this type of cation has been isolated.3a Similarly, [Ph2SnCH2SnPh2·OH]+ has been detected in the ESI mass spectrum of [Ph2SnCH2SnPh2OH(OTf)]29 (compound I; Chart 2) The hydrolysis of spacer-bridged organotin triflates has also been reported.17 From the ESI MS spectrum of 2, the boron-containing hydrolysis product is also evident with a mass cluster at m/z 478.1 assigned to B{3,5(CF3)2C6H3}2+·CH3CN. On the basis of its 1H NMR chemical shifts (δ 8.09, 8.19 ppm), part of the decomposition products observed in solution is assigned to bis(3,5-bis(trifluoromethyl)-

Figure 3. Molecular structure of the cation in 3 with 30% probability ellipsoids. The second molecule, the anion, and the hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Sn(2)−O(2) 2.115(4), Sn(4)−O(4) 2.134(4), C(4)−O(2) 1.255(7), C(4)−O(1) 1.273(7); O(1)−Sn(1)−C(7) 93.06(19), C(7)−Sn(1)− C(1) 130.2(2).

The acetate anion binds in an isobidentate mode to the tin cation with Sn−O distances ranging from 2.115(4) Å (Sn(2)− O(2)) to 2.134(4) Å (Sn(4)−O(4)). The C−O distances range from 1.255(7) Å (C(4)−O(2)) to 1.273(7) Å (C(4)−O(1)). The tin atoms have a distorted-tetrahedral environment with angles ranging from 93.06(19)° (O(1)−Sn(1)−C(7)) to 130.2(2)° (C(7)−Sn(1)−C(1)), which is very similar to the case for compound 1. The ring strain of the six-membered ring is lower than that of the four-membered ring in compound 2. The very low Δν(CO2) value in the IR spectrum of 95 cm−1 in compound 3 underlines the isobidentate bridging binding mode of the acetate moiety.20 Similar to the case for compound 2, the methylene carbon atom is displaced by 0.85 Å from the plane defined by Sn1, Sn2, O1, O2, and C4. The NMR resonances for the acetate moiety are observed at δ 2.31 ppm (1H) and 26.2 and 183.5 ppm (13C), respectively. The 1H and 13C NMR chemical shifts of the BArF4 anion are identical with those observed for compound 2. The 119Sn NMR chemical shift is δ 193 ppm (J(119Sn−117Sn) = 196 Hz). The CMe2 substituents in compounds 2−4 are equivalent on both the 1H and 13C NMR time scales at room temperature, indicating that the ring inversion is fast. 5604


Article

Organometallics On dissolution in CDCl3/toluene at 4 °C, compound 2 slowly hydrolyzed in an atmosphere of water to yield the hydroxido-bridged salt 4 as colorless crystalline blocks (Scheme 1). The neutral distannoxane cyclo-Me2C(SnR)2O (5; R = HC(SiMe3)2) was prepared from compound 1 using sodium hydroxide (Scheme 1), which originated from an attempt to synthesize the selenium-containing four-membered ring. The molecular structures of compounds 4 and 5 are shown in Figures 4 and 5, respectively. Selected interatomic distances and angles are given in the corresponding figure captions.

Figure 5. Molecular structure of the cyclo-distannoxane 5 with 30% probability ellipsoids. The hydrogen atoms are omitted for clarity. Symmetry code: −x + 1, y, −z + 0.5. Selected interatomic distances (Å): Sn(1)−C(1) 2.212(6), Sn(1)−C(4) 2.192(6), Sn(1)−C(5) 2.190(6), Sn(1)−O(3) 2.008(4), Sn(1)−Sn(1A) 3.1074(7). Selected interatomic angles (deg): C(1)−Sn(1)−C(4) 118.50(19), C(1)− Sn(1)−C(5) 122.2(2), C(1)−Sn(1)−O(3) 84.7(2), C(4)−Sn(1)− C(5) 109.8(3), C(4)−Sn(1)−O(3) 113.8(2), C(5)−Sn(1)−O(3) 103.76(19), Sn(1)−C(1)−Sn(1A) 89.3(3), Sn(1)−O(3)−Sn(1A) 101.4(3).

Figure 4. Molecular structure of the cation in 4 with 30% probability ellipsoids. The anion, disorder at Sn(2), and the hydrogen atoms with calculated positions are omitted for clarity. Selected interatomic distances (Å): Sn(1)−O(1) 2.128(3), Sn(2)−O(1) 2.093(3), O(1)− H(1) 0.81(2). Selected interatomic angles (deg): C(1)−Sn(1)−C(4) 119.46(18), C(1)−Sn(1)−C(5) 123.52(17), C(1)−Sn(1)−O(1) 79.64(13), C(4)−Sn(1)−C(5) 114.69(16), C(4)−Sn(1)−O(1) 107.24(13), C(5)−Sn(1)−O(1) 99.20(15), C(1)−Sn(2)−C(6) 112.85(19), C(1)−Sn(2)−C(7) 111.7(2), C(1)−Sn(2)−O(1) 80.25(13), C(6)−Sn(2)−C(7) 131.7(2), C(6)−Sn(2)−O(1) 103.40(16), C(7)−Sn(2)−O(1) 101.37(16), Sn(1)−O(1)−Sn(2) 100.61(11), Sn(1)−C(1)−Sn(2) 95.85(16), Sn(2)−O(1)−H(1) 133(4), Sn(1)−O(1)−H(1) 123(4).

comparison to those in the latter compound, the corresponding Sn−O and Sn−C distances as well as the angles in compound 5 are larger. Interestingly, while cyclo-O(SnR)2O is yellow, compound 5 is colorless. Apparently, the HOMO−LUMO gap in 5 is greater than that in the former compound. An IR spectrum of compound 4 shows a sharp ν(OH) absorption at 3616 cm−1. This is close to the ν(OH) band of 3603 cm−1 reported for [Sn2(CH(SiMe3)2)4(C8H12)(OH)][I3].8a The 1H NMR spectrum shows the OH proton with unresolved tin satellites at δ 2.05 (2J(1H−117/119Sn) = 19 Hz) regardless of the water content of the CDCl3. The integral ratio of satellite to signal to satellite (13:72:15) shows both tin atoms to be equivalent. The coupling constant is lower than observed by Wesemann et al. for a dihydroxy-substituted tetraorganodistannoxane (34−38 Hz)22 or Ar*(Me)2SnOH (Ar* = 2,6Mes,4-t-Bu-C6H3, Mes = 2,4,6-Me-C6H2) with 27 Hz.23 However, the OH signal disappeared on addition of D2O (Figure S6 in the Supporting Information), in a manner analogous to that reported for {(Me3Si)2CH)2}Sn(H)OH.24 This hints at a very slow H/D exchange. No reaction between compound 4 and sodium acetate in CD2Cl2 was observed, pointing to the fact that compound 4 is a weaker acid than acetic acid. Notably, the ESI MS for compound 4 (see the Experimental Section) shows, in addition to a mass cluster assigned to the cation of 4, also mass clusters containing only one tin atom, indicating cleavage of the Sn−C−Sn bridge under ESI-MS conditions. The structure of compound 5 is retained in solution. Thus, the 119Sn NMR spectrum shows only one 117Sn coupling constant equivalent to one tin atom with a signal centered at δ 158 ppm (2J(119Sn−117Sn) = 606 Hz).

The structure of the protonated cyclo-distannoxane 4 very much resembles that of compound 2. The Sn−O−Sn bridge is almost symmetric with Sn(1)−O(1) and Sn(2)−O(1) distances of 2.128(3) and 2.093(3) Å, respectively. These distances are similar to the Sn−O distance of 2.100(6) Å in compound F (Chart 1)8a but clearly longer than the Sn(1)− O(3) distance of 2.008(4) Å in the neutral compound 5. The Sn(1)−O(1)−Sn(2) angle in 4 of 100.61(11)° is rather similar to the Sn(1)−O(3)−Sn(1A) angle in 5 of 101.4(3)°, indicating almost no effect on these values by protonation/deprotonation. The four-membered ring in compound 4 is puckered, similar to the case for the chloride-substituted derivative 2. An almost planar four-membered ring was observed for H 2 C(SnPh2OMe)2·MeOH, with the shortest Sn−O distance being 2.133(2) Å.21a On the other hand, the four-membered ring in compound 5 shows perfect planarity. Perfect planarity was also reported for the four-membered Sn2O2 ring in the diorganotin oxide cyclo-O(SnR)2O (R = HC(SiMe3)2; Sn−O 1.94(2)/ 1.98(1), Sn−C 1.97(3)/2.10(2), Sn−Sn(A) 2.94, O−O′ 2.55 Å; O−Sn−O(A) 82.5(6), Sn−O−Sn(A) 97.5(6)°).21b In 5605


Article

Organometallics

■

1

J(13C−117/119Sn) = 123 Hz, 1J(13C−29Si) = 37 Hz, CH), 28.9 (s, J(13C−117/119Sn) = 11 Hz, CCH3), 54.7 (s, 1J(13C−117/119Sn) = 375/ 392 Hz, CCH3). 29Si{1H} NMR (79.49 MHz, CDCl3): δ 1.01 (s, 2 29 J( Si−117/119Sn) = 24/25 Hz, 1J(29Si−13C) = 51 Hz), 1.40 (s, 2 29 J( Si−117/119Sn) = 28/29 Hz, 1J(29Si−13C) = 51 Hz). 119Sn{1H} NMR (149.2 MHz, CDCl3): δ 118 (bs, ν1/2 = 150 Hz). IR (ATR): ν̃ 2952, 2899, 1266 (shoulder), 1246, 1012, 992, 828, 760, 772, 665, 616, 555, 476, 456 cm−1. ESI MS (+): m/z 809.2 (M − R − Cl + OH, 100%), 791.3 (M − R − 2Cl + 2OH). ESI MS (−): m/z 899.1 (M − R + 2Cl, 100%), 879.2 (M − R + Cl + OH), 843.2 (M − R − Cl + 3OH). Anal. Calcd for C31H82Cl2Si8Sn2 (987.99): C, 37.7; H, 8.4. Found: C, 38.0; H, 8.7. Crystals suitable for X-ray diffraction were grown from CH3CN/acetone, giving 1·0.5C3H6O. The acetone solvate in the voids had evaporated over 1 week, as concluded from an IR spectrum. Synthesis of [cyclo-{Me2C(SnR2)2Cl}B(ArF)4] (2). Compound 1 (541 mg, 0.547 mmol) and NaBArF4 (582 mg, 0.65 mmol) were in stirred in dry CH2Cl2 (6 mL) for 15 min. The suspension was filtered and the solvent removed in vacuo. The colorless air-stable solid was washed with toluene and hexane and dried in vacuo. Yield: 925 mg (0.508 mmol, 93%), Mp: 167−170 °C. 1H NMR (300.13 MHz, CDCl3): δ 0.31 (s, 72H, SiCH3), 1.03 (s, 2J(1H−117/119Sn) = 96/100 Hz, 4J(1H−117/119Sn) = 8 Hz, 4H, CH), 2.28 (s, 3J(1H−117/119Sn) = 111/115 Hz, 6H, CCH3), 7.53 (bs, 4H, para-H), 7.72 (s, 8H, orthoH). 13C{1H} NMR (75.47 MHz, CDCl3): δ 4.64 (s, 3J(13C−117/119Sn) = 20 Hz, 1J(13C−29Si) = 51 Hz, SiCH3), 4.65 (s, 3J(13C−117/119Sn) = 18 Hz, 1J(13C−29Si) = 53 Hz, SiCH3), 24.2 (s, 3J(13C−117/119Sn) = 27/ 32 Hz, CH), 28.5 (s, 2J(13C−117/119Sn) = 12.8 Hz, CCH3), 65.8 (s, 1 13 J( C−117/119Sn) = 267/279 Hz, CCH3), 117.4 (m, CpBAr4), 124.6 (q, 1 13 J( C−19F) = 272 Hz, CF3), 128.9 (qq, 3J(13C−11B) = 2.9 Hz, 2 13 J( C−19F) = 32 Hz, CmBAr4), 134.8 (bs, CoBAr4), 162.1 (q, 1 13 J( C−11B) = 50 Hz, CiBAr4). 29Si{1H} NMR (59.63 MHz, CDCl3): δ 2.43 (s, 2J(29Si−117/119Sn) = 24 Hz), 2.28 (s, 2J(29Si−117/119Sn) = 26 Hz). 119 Sn{ 1 H} NMR (111.92 MHz, CDCl 3 ): δ 347 (s, 2 119 J( Sn−117Sn) = 252 Hz); 11B{1H} NMR (96.29 MHz, CDCl3): δ −6.7 (s, 1J(11B−13C) = 49 Hz). 19F NMR (282.40 MHz, CDCl3): δ −61.5. IR (ATR): ν̃ 2957, 1611 (BArF4), 1353 (BArF4), 1279 (BArF4), 1257, 1119 (BArF4), 835, 767, 713, 665 cm−1. ESI MS (+): m/z 478.1 (B{3,5-(CF3)2C6H3}2+·CH3CN, 100%, partial decomposition of the anion), 519.1 (B{3,5-(CF 3 ) 2 C 6 H 3 } 2 + ·2CH 3 CN, 40%), 953.3 ([(R2Sn)2{μ-C(CH3)2}(μ-Cl)]+, 15%), 933.4 ([(R2Sn)2{μ-C(CH3)2}(μ-OH)]+, 80%, partial hydrolysis under ESI MS conditions). ESI MS (−): m/z 863.1 (BArF4−). Anal. Calcd for C63H94BClF24Si8Sn2 (1815.75): C, 41.7; H, 5.2. Found: C, 41.8; H, 5.35; EDX calcd: F, 25.1; Cl, 1.95; Si, 12.4; Sn, 13.1. Found: F, 25.45; Cl, 1.75; Si, 11.85; Sn, 13.4. Crystals suitable for X-ray diffraction were grown from CDCl3/toluene. Reaction of Compound 1 with AgN(SO2CF3)2: Formation of [(R2Sn)2{μ-C(CH3)2}(μ-Cl)][NTf2]. Compound 1 (149 mg, 0.15 mmol) was stirred with AgN(SO2CF3)2 (123 mg, 0.31 mmol, 2.1 equiv) in CD2Cl2 (1.5 mL) overnight under protection from light. A voluminous, slightly pink solid precipitated which is soluble in NH3(aq). NMR spectra of the CD2Cl2 solution were taken. 1H NMR (300.13 MHz, CD2 Cl2 ): δ 0.33 (s, 72H, SiCH 3 ), 1.06 (s, 2 1 J( H−117/119Sn) = 98 Hz, 4H, CH), 2.30 (s, 3J(1H−117/119Sn) = 114 Hz, 6H, CCH3). 119Sn{1H} NMR (111.92 MHz, CD2Cl2): δ 346 (s, 2 119 J( Sn−117Sn) = 246 Hz). 29Si{1H} NMR (59.63 MHz, CD2Cl2): δ 2.41 (s), 2.28 (s). 19F NMR (282.40 MHz, CDCl3): δ −75.9. Synthesis of [cyclo-{Me2C(SnR2)2OAc}B(ArF)4] (3). Compound 2 (341 mg, 0.188 mmol) was heated to reflux in technical grade EtOAc (25 mL) overnight. The solution was concentrated in vacuo to a volume of approximately 1 mL, and the resulting crystals were washed with toluene and hexane. The crystals were dried in vacuo. Compound 3 was obtained as a colorless, air-stable solid. Yield: 174 mg (0.095 mmol, 50%). Mp: 179−182 °C. 1H NMR (200.13 MHz, CDCl3): δ 0.29 (s, 72H, SiCH3), 0.69 (s, 2J(1H−117/119Sn) = 98/103 Hz, 4 1 J( H−117/119Sn) = 8.6 Hz, 4H, CH), 2.09 (s, 3J(1H−117/119Sn) = 103/ 107 Hz, 6H, CCH3), 2.31 (s, 3H, OOCCH3), 7.53 (bs, 4H, para-H), 7.72 (s, 8H, ortho-H). 13C{1H} NMR (50.33 MHz, CDCl3): δ 4.83 (s,

CONCLUSION Bulky substituents were employed for the kinetic stabilization of bicentric organotin cations, making the corresponding salts air-stable. However, in solution they are susceptible to slow hydrolysis. This appears to be the reason that attempts to use these cations as catalysts for the cleavage of phosphate esters such as dichlorvos failed. The chloride anion in compound 2 is bound so tightly that it is not abstracted by silver salts.

■

2

EXPERIMENTAL SECTION

General Considerations. (RCl2Sn)2CMe2 (R = (Me3Si)2CH)10 and NaBArF425 were prepared as previously described. NMR spectra were recorded on a Bruker AV DPX 300/DRX 400/AVIII 400 or Varian Mercury 200 instrument at room temperature. NMR chemical shifts are given in ppm and were referenced to Me4Si, Me4Sn (119Sn), BF3·OEt2 (11B), or CFCl3 (19F). The IR spectra (cm−1) were recorded on a PerkinElmer Spectrum Two instrument (ATR). Melting points were measured on a Büchi M-560 instrument or a polarization hot stage microscope (VEB Analytik Dresden) (1, 5). Elemental analyses were performed on an Elementar VARIO MICRO Cube or Carlo Erba Sturmantazione MOD 1106 analyzer (1, 5). The electrospray mass spectra were recorded with a Thermoquest-Finnigan instrument using nondried CH3CN as the mobile phase under ambient conditions with a concentration of 0.1 mg/mL and a flow rate of 10 μL/min. The experimental isotopic patterns matched the theoretical patterns. The EDX analysis was performed on a Hitachi REM S4500 instrument combined with an Oxford Link Isis using a voltage of 20 kV. The carbon, hydrogen, and boron analysis is not included, but the values were corrected for the measured values. Crystallography. Intensity data for the crystals (1·0.5C3H6O and 2−4) were collected on a XcaliburS CCD diffractometer (Oxford Diffraction) using Mo Kα radiation at 110 K (temperature of the X-ray source) or an Enraf-Nonius CAD 4 diffractometer using Cu Kα radiation at 296 K (5). The structures were solved with direct methods using SHELXS-2014/726 (1·0.5C3H6O and 2−4) or Sir92.27 Refinements were carried out against F2 by using SHELXL-2014/7.26 The C−H hydrogen atoms were positioned with idealized geometry and refined using a riding model. The O−H proton in compound 4 was located on the difference Fourier map. All non-hydrogen atoms were refined using anisotropic displacement parameters. The Platon Squeeze routine28 was used to model disordered electron densities of the acetone solvate molecule in 1·0.5C3H6O. All compounds are affected by positional disorder regarding SiMe3 or CF3 groups (in 3 and 5) and additionally CH(SiMe3)2 groups (in 2) and tin positions (in 1·0.5C3H6O and 4). Their occupancy values were allowed to refine freely until a constant number was obtained (and an integer value was applied afterward in some cases). If necessary, interatomic 1,2distances between atoms were restrained to be equal and equivalent anisotropic displacement parameters were applied to model disordered parts. For a few atoms Uij components were restrained to approximate isotropic behavior. For further details the files CCDC-1409484 (1· 0.5C3H6O), CCDC-1409485 (2), CCDC-1409486 (3), CCDC1409487 (4) and CCDC-1409488 (5) contain supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www. ccdc.cam.ac.uk/data_request/cif. Synthesis of Me2C(SnClR2)2 (1; R = CH(SiMe3)2). To a stirred solution of (RCl2Sn)2CMe2 (R = (Me3Si)2CH; 3.64 g, 4.92 mmol) in pentane (100 mL) was added a solution of LiCH(SiMe3)2 (1.73 g, 10.41 mmol) in Et2O/pentane (1/10) over a period of 1 h. The reaction mixture was stirred for 12 h and filtered. After evaporation of the solvent in vacuo a colorless solid (4.72 g) was obtained, which was recrystallized from hexane. Yield: 3.5 g (3.54 mmol, 72%); Mp: 190− 192 °C. 1H NMR (400.13 MHz, CDCl3): δ 0.24 (s, 72H, SiCH3), 0.35 (s, 2J(1H−117/119Sn) = 92/96 Hz, 4H, CH), 1.99 (s, 3J(1H−117/119Sn) = 111/116 Hz, 6H, CCH3). 13C{1H} NMR (100.62 MHz, CDCl3): δ 5.1 (s, 3J(13C−117/119Sn) = 16 Hz, 1J(13C−29Si) = 52 Hz, SiCH3), 5.4 (s, 3 13 J( C−117/119Sn) = 17 Hz, 1J(13C−29Si) = 51 Hz, SiCH3), 16.4 (s, 5606


Article

Organometallics

freshly prepared. 1H NMR (200.13 MHz, CDCl3): δ 0.32 (s, 72H, SiCH3), 1.04 (s, 2J(1H−117/119Sn) = 96/100 Hz, 4J(1H−117/119Sn) = 8 Hz, 4H, CH), 2.03 (m, H-4), 2.29 (s, 3J(1H−117/119Sn) = 110/114 Hz, 6H, CCH3), 6.17 (m, H-2), 7.01 (m, H-3), 7.54 (bs, 4H, para-H), 7.73 (s, 8H, ortho-H), 9.36 (d, H-1). A solution of crotonaldehyde in CDCl3 was measured: H-3 δ 6.87.

3

J(13C−117/119Sn) = 20 Hz, 1J(13C−29Si) = 52 Hz, SiCH3), 4.86 (s, J(13C−117/119Sn) = 18 Hz, 1J(13C−29Si) = 52 Hz, SiCH3), 18.7 (s, CH), 26.2 (s, OOCCH3), 27.4 (s, 2J(13C−117/119Sn) = 11.1 Hz, CCH3), 45.1 (s, CCH3), 117.4 (m, CpBAr4), 124.5 (q, 1J(13C−19F) = 272 Hz, CF3), 128.8 (qq, 3J(13C−11B) = 2.9 Hz, 2J(13C−19F) = 31 Hz, CmBAr4), 134.8 (bs, CoBAr4), 161.7 (q, 1J(13C−11B) = 50 Hz, CiBAr4), 183.5 (s, OOCCH3). 29Si{1H} NMR (59.63 MHz, CDCl3): δ 1.93 (s, 2 29 J( Si−117/119Sn) = 26 Hz), 1.90 (s, 2J(29Si−117/119Sn) = 26 Hz). 119 Sn{1H} NMR (111.92 MHz, CDCl3): δ 193 (s, 2J(119Sn−117Sn) = 196 Hz). 11B{1H} NMR (96.29 MHz, CDCl3): δ −6.7 (s, 1J(11B−13C) = 51 Hz). 19F NMR (282.40 MHz, CDCl3): δ −61.5. IR (ATR): ν̃ . 2960, 1611 (BArF4), 1541 (νCOasym), 1446 (νCOsym), 1354 (BArF4), 1276 (BArF4), 1256, 1159, 1118 (BArF4), 835, 767, 715, 680, 668 cm−1. ESI MS (+): m/z 519.1 (B{3,5-(CF3)2C6H3}2+·2CH3CN, 15%), 975.4 ([(R2Sn)2{μ-C(CH3)2}(μ-OAc)]+, 50%), 933.4 ([(R2Sn)2{μC(CH3)2}(μ-OH)]+, 90%, partial hydrolysis under ESI MS conditions). ESI MS (−): m/z 863.1 (BArF4−). Anal. Calcd for C65H97BF24O2Si8Sn2 (1839.34): C, 42.4; H, 5.3. Found: C, 42.1; H, 5.6; Crystals of 3 suitable for X-ray diffraction were grown from an EtOAc/CH 3 CN solution of compound 2 after 1 day. The crystallization vessel gave a smell of acetic acid. Synthesis of [cyclo-{Me2C(SnR2)2OH}B(ArF)4] (4). Compound 2 in a CHCl3/toluene solvent mixture was stored in an open dish in the refrigerator. Over a few weeks colorless blocks of the protonated distannoxane 4 formed, which were washed with toluene and hexane and dried in vacuo. Mp: 199 °C. 1H NMR (200.13 MHz, CDCl3): δ 0.28 (s, 36H, SiCH3), 0.29 (s, 36H, SiCH3), 0.82 (s, 2J(1H−117/119Sn) = 98/103 Hz, 4J(1H−117/119Sn) = 9 Hz, 4H, CH), 2.05 (s, 2 1 J( H−117/119Sn) = 19 Hz, 1H, OH), 2.17 (s, 3J(1H−117/119Sn) = 107/111 Hz, 6H, CCH3), 7.53 (bs, 4H, para-H), 7.72 (s, 8H, orthoH). 13C{1H} NMR (50.33 MHz, CDCl3): δ 4.57 (s, 3J(13C−117/119Sn) = 19 Hz, SiCH3), 4.76 (s, 3J(13C−117/119Sn) = 18 Hz, SiCH3), 21.2 (s, CH), 28.1 (s, 2J(13C−117/119Sn) = 14 Hz, CCH3), 60.4 (s, CCH3), 117.5 (m, CpBAr4), 124.5 (q, 1J(13C−19F) = 272 Hz, CF3), 128.6 (qq, 3 13 J( C−11B) = 2.9 Hz, 2J(13C−19F) = 32 Hz, CmBAr4), 134.8 (bs, CoBAr4), 161.7 (q, 1J(13C−11B) = 50 Hz, CiBAr4); 29Si{1H} NMR (79.52 MHz, CDCl3): δ 1.39 (s), 1.11 (s). 119Sn{1H} NMR (149.62 MHz, CDCl3): δ 300 (bs, W1/2 = 100 Hz). 11B{1H} NMR (128.42 MHz, CDCl3): δ −6.6 (s, 1J(11B−13C) = 49 Hz). 19F NMR (376.61 MHz, CDCl3): δ −62.4. IR (ATR): ν̃ 3616 (sharp, OH), 2961, 1612 (BArF4), 1352 (BArF4), 1275 (BArF4), 1253, 1161, 1121 (BArF4), 827, 768, 714, 681, 667 cm−1. ESI MS (+): m/z 439.1 (OSnR2−CH3+, 30%), 455.1 (HOSnR2+, 40%), 480.2 (OSnR2−CH3·CH3CN, 80%), 496.1 (HOSnR2·CH3CN+, 20%), 519.1 (B{3,5-(CF3)2C6H3}2+· 2CH3CN, 50%), 933.4 ([(R2Sn)2{μ-C(CH3)2}(μ-OH)]+, 100%). ESI MS (−): m/z 863.1 (BArF4−). Anal. Calcd for C63H95BOF24Si8Sn2 (1797.30): C, 42.0; H, 5.3. Found: C, 41.0; H, 5.7. Synthesis of cyclo-{Me2C(SnR2)2O} (5). To a solution of NaHSe (52 mg, 0.505 mmol; prepared from Se (40 mg, 0.505 mmol) and NaBH4 (38 mg, 0.505 mmol)) in H2O (15 mL) was added a suspension of compound 1 (500 mg, 0.505 mmol) in acetone/Et2O (25 mL, 3/1) at 0 °C. The reaction mixture was stirred for 40 h, during which a gray precipitate (Se) appeared. The suspension was filtered, and the solvent was removed in vacuo. The residue was crystallized from CH2Cl2/acetone. Yield: 380 mg (0.407 mmol, 81%). Mp: 210 °C dec. 1H NMR (400.13 MHz, CDCl3): δ 0.19 (s, 40H, SiCH3 + CH), 0.20 (s, 36H, SiCH3), 1.96 (s, 3J(1H−117/119Sn) = 101/ 106 Hz, 6H, CCH3). 13C{1H} NMR (100.62 MHz, CDCl3): δ 4.7 (s, 3 13 J( C−117/119Sn) = 16 Hz, SiCH3), 4.9 (s, 3J(13C−117/119Sn) = 16 Hz, SiCH3), 14.4 (s, 1J(13C−117/119Sn) = 92/97 Hz, 1J(13C−29Si) = 38 Hz, CH), 29.1 (s, 2J(13C−117/119Sn) = 20 Hz, CCH3), 63.7 (s, 1 13 J( C−117/119Sn) = 281/295 Hz, CCH3). 29Si{1H} NMR (79.49 MHz, CDCl3): δ −0.19 (s, 2J(29Si−117/119Sn) = 20/21 Hz), 0.17 (s, 2 29 J( Si−117/119Sn) = 26/27 Hz). 119Sn{1H} NMR (149.2 MHz, CDCl3): δ 158 (s, 2J(119Sn−117Sn) = 606 Hz). Anal. Calcd for C31H82O1Si8Sn2 (933.09): C, 39.9; H, 8.9. Found: C, 40.0; H, 9.1. Estimation of the Lewis Acidity of Compound 2 according to the Childs Method.12 A solution of compound 2 (69 mg, 0.038 mmol) and crotonaldehyde (1.3 mg, 0.019 mmol) in CDCl3 was 3

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.5b00829. Spectra (NMR, IR, ESI, EDX) and crystallographic data (PDF) Crystallographic data (CIF)

■

AUTHOR INFORMATION

Corresponding Author

*E-mail for K.J.: [email protected]. Notes

The authors declare no competing financial interest.

■ ■

ACKNOWLEDGMENTS Dedicated to Professor F. Ekkehardt Hahn on the occasion of his 60th birthday. REFERENCES

(1) (a) Wirth, A.; Moers, O.; Blaschette, A.; Jones, P. G. Z. Anorg. Allg. Chem. 1999, 625, 982−988. (b) Wirth, A.; Lange, I.; Henschel, D.; Moers, O.; Blaschette, A.; Jones, P. G. Z. Anorg. Allg. Chem. 1998, 624, 1308−1318. (c) Wirth, A.; Moers, O.; Blaschette, A.; Jones, P. G. Z. Anorg. Allg. Chem. 1998, 624, 1686−1694. (d) Lange, I.; Henschel, D.; Wirth, A.; Krahl, J.; Blaschette, A.; Jones, P. G. J. Organomet. Chem. 1995, 503, 155−170. (e) Lange, I.; Krahl, J.; Jones, P. G.; Blaschette, A. J. Organomet. Chem. 1994, 474, 97−106. (f) Lange, I.; Wieland, E.; Jones, P. G.; Blaschette, A. J. Organomet. Chem. 1993, 458, 57−61. (g) Blaschette, A.; Hippel, I.; Krahl, J.; Wieland, E.; Jones, P. G.; Sebald, A. J. Organomet. Chem. 1992, 437, 279−297. (h) Blaschette, A.; Schomburg, D.; Wieland, E. Z. Anorg. Allg. Chem. 1989, 571, 75−81. (2) (a) Zharov, I.; Michl, J. In The Chemistry of Organic Germanium, Tin and Lead Compounds; Rappoport, Z., Ed.; Wiley: Chichester, U.K., 2003: Vol. 2, Chapter 10. (b) Müller, T. Adv. Organomet. Chem. 2005, 53, 155−215. (c) Lee, V. Y.; Sekiguchi, A. Organometallic Compounds of Low-Coordinate Si, Ge, Sn and Pb; Wiley: Chichester, U.K., 2010; Chapter 1, pp 1−43. (d) Chitnis, S. S.; Burford, N. Dalton Trans. 2015, 44, 17−29. (e) Swamy, V. S. V. S. N.; Pal, S.; Khan, S.; Sen, S. S. Dalton Trans. 2015, 44, 12903−12923. (3) (a) Bouska, M.; Dostál, L.; Lutter, M.; Glowacki, B.; Ruzickova, Z.; Beck, D.; Jambor, R.; Jurkschat, K. Inorg. Chem. 2015, 54, 6792− 6800. (b) Ochiai, T.; Franz, D.; Irran, E.; Inoue, S. Chem. - Eur. J. 2015, 21, 1−5. (c) Robertson, A. P. M.; Friedmann, J. N.; Hilary, A.; Jenkins, H. A.; Burford, N. Chem. Commun. 2014, 50, 7979−7981. (d) Krabbe, S.; Wagner, M.; Löw, C.; Dietz, C.; Schürmann, M.; Hoffmann, A.; Herres-Pawlis, S.; Lutter, M.; Jurkschat, K. Organometallics 2014, 33, 4433−4441. (e) Reißmann, M.; Schäfer, A.; Jung, S.; Müller, T. Organometallics 2013, 32, 6736−6744. (f) Schwedtmann, K.; Holthausen, M. H.; Feldmann, K.-O.; Weigand, J. J. Angew. Chem., Int. Ed. 2013, 52, 14204−14208. (g) Li, J.; Schenk, C.; Winter, F.; Scherer, H.; Trapp, N.; Higelin, A.; Keller, S.; Pöttgen, R.; Krossing, I.; Jones, C. Angew. Chem., Int. Ed. 2012, 51, 9557−9561. (h) Budanow, A.; Sinke, T.; Tillmann, J.; Bolte, M.; Wagner, M.; Lerner, H.-W. Organometallics 2012, 31, 7298−7301. (i) MacDonald, E.; Doyle, L.; Burford, N.; Werner-Zwanziger, U.; Decken, A. Angew. Chem., Int. Ed. 2011, 50, 11474−11477. (j) Romanato, P.; Duttwyler, S.; Linden, A.; Baldridge, K. K.; Siegel, J. S. J. Am. Chem. Soc. 2011, 133, 11844− 11846. (k) Lühmann, N.; Hirao, H.; Shaik, S.; Müller, T. Organo5607


Article

Organometallics metallics 2011, 30, 4087−4096. (l) Ibad, M. F.; Langer, P.; Schulz, A.; Villinger, A. J. Am. Chem. Soc. 2011, 133, 21016−21027. (m) Kašná, B.; Dostál, L.; Císařová, I.; Jambor, R. Organometallics 2007, 26, 4080− 4082. (4) (a) Farrell, J. M.; Stephan, D. W. Chem. Commun. 2015, 51, 14322−14325. (b) Holthausen, M. H.; Bayne, J. M.; Mallov, I.; Dobrovetsky, R.; Stephan, D. W. J. Am. Chem. Soc. 2015, 137, 7298− 7301. (c) Jiang, C.; Blacque, O.; Berke, H. Chem. Commun. 2009, 5518−5520. (d) Uhl, W.; Vinogradov, A.; Grimme, S. J. Am. Chem. Soc. 2007, 129, 11259−11264. (5) Selected references: (a) Wendji, A. S.; Lutter, M.; Dietz, C.; Jouikov, V.; Jurkschat, K. Organometallics 2013, 32, 5720−5730. (b) Zhao, F.; Gabbaï, F. P. Organometallics 2012, 31, 2327−2335. (c) Wade, C. R.; Gabbaï, F. P. Organometallics 2011, 30, 4479−4481. (d) Zhao, H.; Gabbaï, F. P. Nat. Chem. 2010, 2, 984−990. (e) Hudnall, T. W.; Chiu, C.-W.; Gabbaï, F. P. Acc. Chem. Res. 2009, 42, 388−397. (f) Kawachi, A.; Tani, A.; Shimada, J.; Yamamoto, Y. J. Am. Chem. Soc. 2008, 130, 4222−4223. (g) Reeske, G.; Bradtmöller, G.; Schürmann, M.; Jurkschat, K. Chem. - Eur. J. 2007, 13, 10239−10245. (h) Lee, M. H.; Gabbaï, F. P. Inorg. Chem. 2007, 46, 8132−8138. (i) Boshra, R.; Venkatasubbaiah, K.; Doshi, A.; Lalancette, R. A.; Kakalis, L.; Jäkle, F. Inorg. Chem. 2007, 46, 10174−10186. (j) Venkatasubbaiah, K.; Bats, J. W.; Rheingold, A. L.; Jäkle, F. Organometallics 2005, 24, 6043−6050. (k) Chaniotakis, N.; Jurkschat, K.; Müller, D.; Perdikaki, K.; Reeske, G. Eur. J. Inorg. Chem. 2004, 2004, 2283−2288. (l) Bayer, M. J.; Jalisatgi, S. S.; Smart, B.; Herzog, A.; Knobler, C. B.; Hawthorne, M. F. Angew. Chem., Int. Ed. 2004, 43, 1854−1857. (m) Hoefelmeyer, J. D.; Schulte, M.; Tschinkl, M.; Gabbaï, F. P. Coord. Chem. Rev. 2002, 235, 93−103. (n) Perdikaki, K.; Tsagkatakis, I.; Chaniotakis, N. A.; Altmann, R.; Jurkschat, K.; Reeske, G. Anal. Chim. Acta 2002, 467, 197−204. (o) Schulte, M.; Schürmann, M.; Jurkschat, K. Chem. - Eur. J. 2001, 7, 347−355. (p) Altmann, R.; Gausset, O.; Horn, D.; Jurkschat, K.; Schürmann, M.; Fontani, M.; Zanello, P. Organometallics 2000, 19, 430−443. (q) Wuest, J. D. Acc. Chem. Res. 1999, 32, 81. (r) Vaugeois, J.; Wuest, J. D. J. Am. Chem. Soc. 1998, 120, 13016−13022. (s) Tsagatakis, J. K.; Chaniotakis, N. A.; Jurkschat, K. Quimica Analitica 1997, 16, 105−109. (t) Altmann, R.; Jurkschat, K.; Schürmann, M.; Dakternieks, D.; Duthie, A. Organometallics 1997, 16, 5716−5723. (u) Dakternieks, D.; Jurkschat, K.; Zobel, B.; Tiekink, E. R. T. Z. Kristallogr. - Cryst. Mater. 1996, 211, 757−758. (v) Dakternieks, D.; Jurkschat, K.; Zhu, H. J.; Tiekink, E. R. T. Organometallics 1995, 14, 2512−2521. (w) Tamao, K.; Hayashi, T.; Ito, Y.; Shiro, M. Organometallics 1992, 11, 2099−2114. (x) Jurkschat, K.; Hesselbarth, F.; Dargatz, M.; Lehmann, J.; Kleinpeter, E.; Tzschach, A. J. Organomet. Chem. 1990, 388, 259−271. (y) Newcomb, M.; Horner, J. H.; Blanda, M. T.; Squattrito, P. J. J. Am. Chem. Soc. 1989, 111, 6294−6301. (z) Hyde, J. R.; Karol, T. J.; Hutchinson, J. P.; Kuivila, H. G.; Zubieta, J. A. Organometallics 1982, 1, 404−405. (aa) Altmann, R.; Jurkschat, K.; Schürmann, M.; Dakternieks, D.; Duthie, A. Organometallics 1998, 17, 5858−5866. (6) (a) Maruoka, K. Bull. Chem. Soc. Jpn. 2009, 82, 917−930. (b) Durand, S.; Sakamoto, K.; Fukuyama, T.; Orita, A.; Otera, J.; Duthie, A.; Dakternieks, D.; Schulte, M.; Jurkschat, K. Organometallics 2000, 19, 3220−3223. (c) Gabriele, M.; Kuivila, H. G.; Cochran, J. C. Main Group Met. Chem. 1998, 21, 207−210. (d) Li, Z.; Chansaenpak, K.; Liu, S.; Wade, C. R.; Zhao, H.; Conti, P. S.; Gabbaï, F. P. MedChemComm 2012, 3, 1305−1308. (7) (a) Kordts, N.; Borner, C.; Panisch, R.; Saak, W.; Müller, T. Organometallics 2014, 33, 1492−1498. (b) Müller, T. Angew. Chem., Int. Ed. 2001, 40, 3033−3036. (8) (a) Sita, L. R.; Kinoshita, I.; Lee, S. P. Organometallics 1990, 9, 1644−1650. (b) Belcher, W. J.; Brothers, P. J.; Meredith, A. P.; Rickard, C. E. F.; Ware, D. C. J. Chem. Soc., Dalton Trans. 1999, 2833− 2836. (c) Sakamoto, K.; Ikeda, H.; Akashi, H.; Fukuyama, T.; Orita, A.; Otera, J. Organometallics 2000, 19, 3242−3248. (9) Beckmann, J.; Dakternieks, D.; Duthie, A.; Mitchell, C. Organometallics 2004, 23, 6150−6159. (10) Zobel, B.; Schürmann, M.; Jurkschat, K.; Dakternieks, D.; Duthie, A. Organometallics 1998, 17, 4096−4104.

(11) Wagner, M.; Lutter, M.; Zobel, B.; Hiller, W.; Prosenc, M. H.; Jurkschat, K. Chem. Commun. 2015, 51, 153−156. (12) Meunier-Piret, J.; van Meerssche, M.; Jurkschat, K.; Gielen, M. J. Organomet. Chem. 1985, 288, 139−143. (13) Pyykkö, P.; Atsumi, M. Chem. - Eur. J. 2009, 15, 186−197. (14) Mantina, M.; Chamberlin, A. C.; Valero, R.; Cramer, C. J.; Truhlar, D. G. J. Phys. Chem. A 2009, 113, 5806−5812. (15) Strauss, S. H. Chem. Rev. 1993, 93, 927−942. (16) Childs, R. F.; Mulholland, D. L.; Nixon, A. Can. J. Chem. 1982, 60, 801−808. (17) Beckmann, J.; Dakternieks, D.; Duthie, A.; Kuan, F. S.; Tiekink, E. R. T. Organometallics 2003, 22, 4399−4404. (18) Lai, Y.-Y.; Bornand, M.; Chen, P. Organometallics 2012, 31, 7558−7565. (19) Bourke, S. C.; MacLachlan, M. J.; Lough, A. J.; Manners, I. Chem. - Eur. J. 2005, 11, 1989−2000. (20) Deacon, G. B.; Phillips, R. J. Coord. Chem. Rev. 1980, 33, 227− 250. (21) (a) Beckmann, J.; Jurkschat, K.; Schürmann, M. J. Organomet. Chem. 2001, 626, 49−52. (b) Edelman, M.; Hitchcock, P. B.; Lappert, M. J. Chem. Soc., Chem. Commun. 1990, 1116−1118. (22) Henning, J.; Eichele, K.; Fink, R. F.; Wesemann, L. Organometallics 2014, 33, 3904−3918. (23) Mehring, M.; Nolde, C.; Schürmann, M. Inorg. Chim. Acta 2009, 362, 745−752. (24) Schager, F.; Goddard, R.; Seevogel, K.; Pörschke, K.-R. Organometallics 1998, 17, 1546−1551. (25) Yakelis, N. A.; Bergman, R. G. Organometallics 2005, 24, 3579− 3581. (26) (a) Sheldrick, G. M. Acta Crystallogr., Sect. C: Struct. Chem. 2015, 71, 3−8. (b) Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008, 64, 112−122. (27) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl. Crystallogr. 1993, 26, 343−350. (28) Spek, A. L. Acta Crystallogr., Sect. C: Struct. Chem. 2015, 71, 9− 18.

5608


Cyclic Dinuclear Organotin Cations Stabilized by Bulky Substituents

Recommend Documents