Formation Principles for Templated Vanadium Selenite Oxalates

Aug 8, 2013 - The compositions of the reaction mixture dictate the form of the secondary building units from which [(VO)2(C2O4)(SeO3)2]n2n– layers a...
0 downloads 3 Views 3MB Size
Download PDF
Article pubs.acs.org/crystal

Formation Principles for Templated Vanadium Selenite Oxalates Jacob H. Koffer,† Jacob H. Olshansky,† Matthew D. Smith,† Kristen J. Hernandez,‡ Matthias Zeller,‡ Gregory M. Ferrence,§ Joshua Schrier,† and Alexander J. Norquist*,† †

Department of Chemistry, Haverford College, Haverford, Pennsylvania 19041, United States Department of Chemistry, Youngstown State University, Youngstown, Ohio 44555, United States § Department of Chemistry, Illinois State University, Normal, Illinois 61790, United States ‡

S Supporting Information *

ABSTRACT: A set of formation principles governing organically templated vanadium selenite oxalates are described in the context of nine new compounds. The compositions of the reaction mixture dictate the form of the secondary building units from which [(VO)2(C2O4)(SeO3)2]n2n− layers are constructed. The strength of hydrogen-bonding interactions is maximized in these compounds, directly affecting the orientations of the organic ammonium cations and enabling amine packing efficiency to affect layer tessellation. The orientations of selenite stereoactive lone pairs are driven by the minimization of internal void space. Compound symmetry can be directed to chiral space groups through the use of chiral components, with the use of either (R)-2-methylpiperazine or (S)-2-methylpiperazine, resulting in noncentrosymmetric, polar, chiral structures that crystallize in the space group P21 (No. 4).

■

INTRODUCTION

stereoactive lone pairs is a well-known route to new noncentrosymmetric materials.13−21 The focus of the work presented here is two-fold. First, we have expanded the number of reported templated vanadium selenite oxalates from 122 to 10. We have incorporated seven different organic ammonium cations into nine new compounds in which two distinct [(VO)2(C2O4)(SeO3)2]n2n− layer topologies are observed. Second, we have elucidated the principles that govern the formation of these compounds and demonstrate the importance of hydrogen-bonding, three-dimensional packing, and both amine size and symmetry. The directed synthesis of specific structure types is only possible through the determination of such formation principles.

Organic−inorganic hybrid materials have been the focus of intense interest for many years, owing to a wide range of desirable physical properties such materials can exhibit. Specific attention has been given to compounds in which inorganic and organic components are connected through oxygen bridges, with metal organic frameworks (MOFs) representing an important example. While the organic components vary widely in size, structure, and composition, the utility of oxalate linkers is wellestablished. The oxalate moiety exhibits a wide range of coordination modes, offers electronic pathways for magnetic superexchange,1,2 enhances redox properties of lithium-ion battery cathode materials,3 is used widely in coordination compounds,4,5 and can be incorporated into a range of framework materials.6−12 In contrast to much of MOF chemistry, the design of most organic inorganic hybrid materials remains elusive, with little or no control possible over the observed inorganic connectivities. As the properties described above are all structure-dependent, the full understanding of the possible utility of these compounds requires a better exploration of the compositional and structural diversity of these systems and the elucidation of the principles that govern their formations. Specific attention has been focused on organically templated vanadium selenite oxalates for two reasons. First, the recent extension of cathode materials for lithium-ion batteries to include metal-centered oxalato complexes3 underscores the need to fully investigate the structure− property relationship in such materials. Second, the use of high valent early transition metals and main group cations exhibiting © XXXX American Chemical Society

■

EXPERIMENTAL SECTION

Materials. 1,4-Dimethylpiperazine (1,4-dmpip, 98%), N,N′-dimethylethylenediamine (dmed, 99%), N,N,N′,N′-tetramethylethylenediamine (tmed, 99%), N,N-dimethyl-N′-ethylethylenediamine (dmeed, 98%), 1-methylpiperazine (1-mpip, 99%), 2-methylpiperazine (2-mpip, 95%), and Na2C2O4 (99.5%) were purchased from Sigma-Aldrich. NaVO3 (96%), SeO2 (99.4%), trans-2,5-dimethylpiperazine (2,5-dmpip, 98%), (S)-(+)-2-methylpiperazine ((S)-2-mpip, 98+%), and (R)-(−)-2methylpiperazine ((R)-2-mpip, 98+ %) were purchased from Alfa Aesar. All reagents were used as received. Deionized water was used in these syntheses. Synthesis. All reactions were conducted in 15 mL polypropylene bottles. The approximate molar composition of each reaction was 1 Received: July 2, 2013 Revised: August 6, 2013

A

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

Table 1. Crystallographic Data for Compounds 1−8b

formula fw space group a/Å b/Å c/Å α/deg β/deg γ/deg V/Å3 Z ρcalc/g cm−3 λ/Å T/K μ/mm−1 Flack parameter R1a wR2b

formula fw space group a/Å b/Å c/Å α/deg β/deg γ/deg V/Å3 Z ρcalc/g cm−3 λ/Å T/K μ/mm−1 Flack parameter R1a wR2b a

[C6H16N2][(VO)2(C2O4)(SeO3)] (1)

[C6H16N2][(VO)2(C2O4)(SeO3)]·2H2O (2)

[C4H14N2][(VO)2(C2O4)(SeO3)]·2H2O (3)

[C6H18N2][(VO)2(C2O4)(SeO3)] (4)

C8H16N2O12Se2V2 592.02 P1̅ (No. 2) 6.324(3) 7.841(4) 9.197(5) 90.438(7) 105.955(7) 105.059(7) 421.9(4) 1 2.330 0.71073 100 5.487

C8H20N2O14Se2V2 628.05 P1̅ (No. 2) 9.024(5) 9.571(5) 12.313(5) 68.243(5) 73.643(5) 82.752(5) 947.4(8) 2 2.201 0.71073 100 4.901

C6H18N2O14Se2V2 602.02 P1̅ (No. 2) 6.3369(16) 8.509(2) 9.413(2) 95.363(3) 108.245(3) 105.236(3) 456.5(2) 1 2.190 0.71073 100 5.081

C8H18N2O12Se2V2 594.04 P1̅ (No. 2) 6.378(7) 8.444(7) 9.405(8) 92.260(16) 107.27(3) 107.84(2) 455.6(8) 1 2.165 0.71073 100 5.081

0.0287 0.0594 [C6H18N2][(VO)2(C2O4)(SeO3)]·H2O (5)

0.0218 0.0651 [C5H14N2][(VO)2(C2O4)- [C5H14N2][(VO)2(C2O4)(SeO3)]·2H2O (6) (SeO3)]·2H2O (7)

C8H20N2O13Se2V2 612.05 P1̅ (No. 2) 6.3220(8) 8.5056(11) 9.3970(12) 95.3642(19) 108.2669(17) 105.1221(18) 454.68(10) 1 2.235 0.71073 100 5.099

C7H18N2O14Se2V2 614.03 P1̅ (No. 2) 9.290(3) 9.723(3) 11.280(3) 110.687(4) 90.346(4) 114.511(4) 853.3(4) 2 2.390 0.71073 100 5.439

C7H18N2O14Se2V2 614.03 P21/c (No. 14) 9.2248(2) 11.2499(3) 9.3512(2) 90 116.3783(15) 90 869.41(4) 2 2.345 0.71073 100 5.338

0.0411 0.0902

0.0374 0.0781

0.0221 0.0532

0.0265 0.0766 [(R)-C5H14N2][(VO)2(C2O4)(SeO3)]·2H2O (8a)

0.0184 0.0464 [(S)-C5H14N2][(VO)2(C2O4)(SeO3)]·2H2O (8b)

C7H18N2O14Se2V2 614.03 P21 (No. 4) 9.227(5) 11.244(5) 9.362(5) 90 116.077(5) 90 872.4(8) 2 2.337 0.71073 100 5.320 0.06(3) 0.0337 0.0733

C7H18N2O14Se2V2 614.03 P21 (No. 4) 9.2250(15) 11.2463(18) 9.3681(15) 90 116.074(2) 90 873.0(2) 2 2.336 0.71073 100 5.316 0.03(3) 0.0316 0.0737

R1 = ∑∥Fo| − |Fc∥/∑|Fo|. bwR2 = [∑w(Fo2 − Fc2)2/[∑w(Fo2)2]1/2. [C4H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (3). 3 was synthesized through the reaction of 0.1241 g (1.02 × 10−3 mol) of NaVO3, 1.1133 g (1.00 × 10−2 mol) of SeO2, 0.0894 g (1.02 × 10−3 mol) of dmed, 0.1404 g (1.26 × 10−3 mol) of Na2C2O4, and 6.3044 g (0.350 mol) of deionized water. Blue-green plates were recovered in 51% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 11.4 (11.9); H, 3.54 (2.99); N, 4.37 (4.65); V, 24.83 (26.2); Se, 16.4 (16.9). IR data: O−H 3455 cm−1, C−H 3014 cm−1, N−H 1654, 1477 cm−1, VO 952 cm−1, Se−O 805 cm−1. [C6H18N2][(VO)2(C2O4)(SeO3)2] (4). 4 was synthesized through the reaction of 0.1243 g (1.02 × 10−3 mol) of NaVO3, 1.1153 g (1.00 × 10−2 mol) of SeO2, 0.1509 g (1.30 × 10−3 mol) of tmed, 0.1342 g (1.21 × 10−3 mol) of Na2C2O4, and 6.0412 g (0.336 mol) of deionized water. Blue-green prisms were recovered in 74% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 16.6 (16.2); H, 3.17 (3.03); N, 4.59 (4.72); V, 26.3 (26.6); Se, 17.2 (17.1). IR data: O−H 3462 cm−1, C−H 3033 cm−1, N−H 1659, 1468 cm−1, VO 962 cm−1, Se−O 807 cm−1. [C6H18N2][(VO) 2(C2O4)(SeO3) 2]·H2O (5). 5 was synthesized through the reaction of 0.1202 g (0.990 × 10−3 mol) of NaVO3, 0.8962 g (0.808 × 10−2 mol) of SeO2, 0.1135 g (0.980 × 10−3 mol) of dmeed, 0.1379 g (1.24 × 10−3 mol) of Na2C2O4, and 6.1600 g (0.342 mol) of deionized water. Blue-green plates were recovered in 55% yield,

NaVO3:8 SeO2:1 amine:1 Na2C2O4:300 H2O. The pH of each reaction mixture was adjusted to 2 upon the addition of 0.5 mL of 12 M HCl. Reaction mixtures were stirred for 10 min before heating to 90 °C in an oil bath for 24 h. The bottles were opened in air, and products were recovered through vacuum filtration. [C6H16N2][(VO)2(C2O4)(SeO3)2] (1). 1 was synthesized through the reaction of 0.1231 g (1.01 × 10−3 mol) of NaVO3, 1.1105 g (1.01 × 10−2 mol) of SeO2, 0.1140 g (1.00 × 10−3 mol) of 1,4-dmpip, 0.1383 g (1.25 × 10−3 mol) of Na2C2O4, and 6.0056 g (0.336 mol) of deionized water. Blue-green blocks were recovered in 74% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 15.3 (15.3); H, 3.01 (3.20); N, 4.40 (4.46); V, 24.8 (25.2); Se, 15.7 (16.2). IR data: O−H 3452 cm−1, C−H 3029 cm−1, N−H 1650, 1470 cm−1, VO 964 cm−1, Se−O 807 cm−1. [C6H16N2][(VO)2(C2O4)(SeO3)2]·2H2O (2). 2 was synthesized through the reaction of 0.1281 g (1.05 × 10−3 mol) of NaVO3, 1.1283 g (1.02 × 10−2 mol) of SeO2, 0.1466 g (1.29 × 10−3 mol) of 2,5-dmpip, 0.1331 g (1.20 × 10−3 mol) of Na2C2O4, and 6.0277 g (0.335 mol) of deionized water. Blue-green prisms were recovered in 34% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 15.5 (16.2); H, 3.14 (2.70); N, 4.45 (4.73); V, 24.8 (26.7); Se, 16.7 (17.2). IR data: O−H 3455 cm−1, C−H 3016 cm−1, N−H 1664, 1554, 1482 cm−1, VO 948 cm−1, Se−O 808 cm−1. B

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

6 × 6 × 6 Monkhorst−Pack grid. Electron localization functions (ELFs) were computed from the self-consistent valence electron density. ELFs were visualized using Vesta v1.1.029 with an isosurface value of 0.96. Partial atomic charge determinations were performed using the iterative-Hirshfeld scheme (Hirshfeld-I)30,31 on the self−consistent valence electron density using the Cut3D program and promolecule allelectron atomic charge densities generated using the HF96 atomic Hartree−Fock code32 following the method described in our previous work.14,19,33,34 Bond Valence Sums. Oxidation states were verified and hydrogenbonding networks were analyzed using bond valence sums,35 using parameters compiled by Brese and O’Keeffe.36 Complete tables of bond valence sums for compounds 1−8b are available in the Supporting Information.

based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 15.7 (15.7); H, 2.61 (3.27); N, 4.50 (4.58); V, 23.6 (25.8); Se, 16.8 (16.6). IR data: O−H 3455 cm−1, C−H 3014 cm−1, N−H 1653, 1477 cm−1, VO 952 cm−1, Se−O 805 cm−1. [C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (6). 6 was synthesized through the reaction of 0.1212 g (0.990 × 10−3 mol) of NaVO3, 1.1146 g (1.00 × 10−2 mol) of SeO2, 0.1064 g (1.06 × 10−3 mol) of 1-mpip, 0.1354 g (1.22 × 10−3 mol) of Na2C2O4, and 6.0395 g (0.336 mol) of deionized water. Blue-green blocks were recovered in 74% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 13.7 (13.7); H, 2.70 (2.93); N, 4.50 (4.56); V, 24.6 (25.7); Se, 15.9 (16.6). IR data: O−H 3460 cm−1, C−H 3010 cm−1, N−H 1652, 1465 cm−1, VO 954 cm−1, Se−O 808 cm−1. [C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (7). 7 was synthesized through the reaction of 0.1225 g (1.00 × 10−3 mol) of NaVO3, 1.1273 g (1.01 × 10−2 mol) of SeO2, 0.1184 g (1.18 × 10−3 mol) of 2-mpip, 0.1367 g (1.23 × 10−3 mol) of Na2C2O4, and 6.1269 g (0.340 mol) of deionized water. Blue-green blocks were recovered in 15% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 12.7 (13.7); H, 2.70 (2.90); N, 4.50 (4.56); V, 24.6 (25.7); Se, 16.4 (16.6). IR data: O−H 3437 cm−1, C−H 3163 cm−1, N−H 1644, 1549, 1453 cm−1, VO 965 cm−1, Se−O 809 cm−1. [(R)-C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (8a). 8a was synthesized through the reaction of 0.1311 g (1.08 × 10−3 mol) of NaVO3, 1.9773 g (0.880 × 10−2 mol) of SeO2, 0.1113 g (1.11 × 10−3 mol) of (R)-2-mpip, 0.1407 g (1.27 × 10−3 mol) of Na2C2O4, and 6.0881 g (0.338 mol) of deionized water. Blue-green blocks were recovered in 33% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 13.6 (13.7); H, 2.12 (2.93); N, 4.48 (4.56); V, 23.9 (25.7); Se, 17.6 (16.6). IR data: O−H 3375 cm−1, C−H 2985 cm−1, N−H 1647, 1454 cm−1, VO 964 cm−1, Se−O 810 cm−1. [(S)-C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (8b). 8b was synthesized through the reaction of 0.1298 g (1.06 × 10−3 mol) of NaVO3, 0.8944 g (0.806 × 10−2 mol) of SeO2, 0.1116 g (1.12 × 10−3 mol) of (S)-2-mpip, 0.1625 g (1.46 × 10−3 mol) of Na2C2O4, and 6.0695 g (0.337 mol) of deionized water. Blue-green blocks were recovered in 33% yield, based upon vanadium. Elemental microanalysis for 1 obsd (calcd): C, 13.5 (13.7); H, 2.68 (2.93); N, 4.45 (4.56); V, 22.9 (25.7); Se, 17.4 (16.6). IR data: O−H 3373 cm−1, C−H 3002 cm−1, N−H 1647, 1454 cm−1, VO 969 cm−1, Se−O 810 cm−1. Single-Crystal X-ray Diffraction. Data were collected using either Bruker AXS Smart Apex or ApexII CCD diffractometers with Mo Kα radiation (λ = 0.71073 Å). A single crystal was mounted on a Mitegen micromesh mount using a trace of mineral oil and cooled in situ to 100(2) K for data collection. Frames were collected, indexed, and processed, and the files were scaled and corrected for absorption using APEX2.23 The heavy atom positions were determined using SIR92.24 All other non-hydrogen sites were located from Fourier difference maps. All non-hydrogen sites were refined using anisotropic thermal parameters using full-matrix least-squares procedures on Fo2 with I > 3σ(I). Hydrogen atoms were placed in geometrically idealized positions. All calculations were performed using CRYSTALS v14.23c.25 Relevant crystallographic data are listed in Table 1. Powder X-ray Diffraction. Powder diffraction patterns were recorded on a GBC-Difftech MMA powder diffractometer. Samples were mounted on aluminum plates. Calculated powder patterns were generated from single-crystal data using ATOMS v.6.0.26 Bulk powder diffraction patterns for each compound matched calculated patterns, indicating relative phase purity. Infrared Spectroscopy. Infrared measurements were obtained using a PerkinElmer FT-IR Spectrum 1000 spectrophotometer. Samples were diluted with spectroscopic grade KBr and pressed into pellets. Scans were run over the range of 400−4000 cm−1. Electronic Structure Calculations. Solid-state electronic structure calculations were performed using ABINIT v6.4.1 and v6.12.1,27,28 using the Perdew−Burke−Ernzerhof generalized gradient approximation (PBE-GGA) exchange-correlation functional, norm-conserving Trollier−Martins pseudopotentials, and a plane-wave basis set with an energy cutoff of 25 hartree, and utilizing the experimental crystal structures. Sampling of the Brillouin zone was performed with a

■

RESULTS AND DISCUSSION The inorganic components in compounds 1−8b all share the formula [(VO)2(C2O4)(SeO3)2]n2n−. The vanadium(IV) centers all exhibit distorted octahedral coordination geometries. The V−Oterminal bond distances range between 1.5792(5) and 1.625(4) Å, whereas the V−O bridging bonds have distances between 1.9772(17) and 2.3099(7) Å. The selenium sites have oxidation states of 4+ and have trigonal-pyramidal geometries with stereoactive lone pairs. No oxide anions in the [SeO3] groups are protonated. The Se−Obridging distances range between 1.661(6) and 1.726(3) Å. The calculated bond valence sums for vanadium and selenium range from 3.93 to 4.13 v.u. and 3.98 to 4.15 v.u., respectively. Each [VO6] coordination polyhedron in 1−8b is linked to another [VO6] through a bridging oxalate anion, creating [(VO)2(C2O4)] dimers. Three additional oxide anions in each [VO6] octahedron bridge to adjacent [SeO3] groups, resulting in

Figure 1. Ball-and-stick representations of the [(VO)2(C2O4)(SeO3)6] SBUs in (a) 1−5, (b) [C4H12N2][(VO)2(C2O4)(SeO3)], and (c) 6−8b. Green, purple, red, and white spheres represent vanadium, selenium, oxygen, and carbon atoms, respectively. ELF isosurfaces are shown with a boundary condition of 0.96. C

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

compounds 6−8b contain smaller amines (1-mpip and 2-mpip) and result in type-2 layers. In each of these compounds, the orientations of the organic cations with respect to the inorganic layers are dictated by steric effects and hydrogen-bonding. They lie parallel to the inorganic layers and form strong N−H···O hydrogen bonds to adjacent inorganic layers. See Figure 3.

the formation of [(VO)2(C2O4)(SeO3)6] secondary building units (SBUs). In fact, all reported organically templated vanadium selenite oxalates contain these SBUs.22 The only differences between the SBUs in these compounds stem from the orientations of their [SeO3] groups. See Figure 1. Only two distinct connectivities are observed in the inorganic components of the known templated vanadium selenite oxalates (1−8b and [C4H12N2][(VO)2(C2O4)(SeO3)2]22). See Figure 2.

Figure 2. Polyhedral representations of the (a) type-1 and (b) type-2 layer topologies. Green polyhedra represent [VO6], while purple, red and white spheres represent selenium, oxygen and carbon atoms, respectively. ELF isosurfaces are shown with a boundary condition of 0.96.

Figure 3. Three-dimensional packing figures of (a) 1, (b) 6, and (c) [C4H12N2][(VO)2(C2O4)(SeO3)]. Green octahedra represent [VO6], while purple, red, blue, and white spheres represent selenium, oxygen, nitrogen, and carbon atoms, respectively. ELF isosurfaces are shown with a boundary condition of 0.96. Hydrogen atoms have been removed for clarity. Hydrogen-bonding interactions are shown as dashed lines.

The zero-dimensional SBUs described above yield either a rectangular tessellation (type-1) or a herringbone (type-2) layer, shown in Figure 2a,b, respectively. The type-1 layer topology is related to vanadium3,37 and iron38 phosphate oxalates. Note that the [SeO3] orientations in the type-1 layers correspond exclusively to the SBUs shown in Figure 1a,b, while the type-2 layers are constructed only from the SBUs shown in Figure 1c. To understand the formation of these compounds, one must understand the forces that govern structures of the SBUs and the influences that dictate layer topology. The formation of compounds 1−8b and [C4H12N2][(VO)2(C2O4)(SeO3)2] depends upon several factors. First, the structures of the building units from which these compounds are constructed depend upon the composition of the respective reaction mixture. Compounds 1−8b were all synthesized under nearly identical conditions, using reaction mixtures with the approximate compositions of 1 NaVO3:8 SeO2:1 amine:1 Na2C2O4:300 H2O. As the only difference between reaction mixtures is the identity of the amine, any differences in the compound structures should be the result of the amine structure. Second, the strengths of the hydrogenbonding networks are maximized in each compound. This forces the organic amines in 1−8b to lie parallel to their respective inorganic layers and affects the inclusion or exclusion of water molecules from each compound. Third, inter-layer void space is minimized, affecting layer separation distances and the orientations of the [SeO3] groups. These principles can be used to understand the formation of all templated vanadium selenite oxalates. Compounds 1−5 contain larger amines (1,4-dmpip, 2,5-dmpip, dmed, tmed and dmeed), and all adopt type-1 layers, whereas

However, the orientations of the cations with respect to one another are dictated by cation size, which is approximated by their respective “footprints” or layer areas per organic cation. See Table 2. The smaller amines pack more closely together in order Table 2. Organic Cation Footprint in Compounds 1−8b compound

amine

footprint (Å2)

layer type

1 2 3 4 5 6 7 8a 8b

[1,4-dmpipH2]2+ [2,5-dmpipH2]2+ [dmedH2]2+ [tmedH2]2+ [dmeedH2]2+ [1-mpipH2]2+ [2-mpipH2]2+ [(R)-2-mpipH2]2+ [(R)-2-mpipH2]2+

55.9(1) 54.7(2) 56.65(4) 57.3(6) 56.4(1) 52.38(9) 52.60(4) 52.6(2) 52.6 (3)

type-1 type-1 type-1 type-1 type-1 type-2 type-2 type-2 type-2

to minimize the void space between inorganic layers.33 This causes a contraction in the inorganic layers, owing to the need for charge neutrality. The correlation is clear, with all the “larger” cations adopting type-1 topologies and all the “smaller” cations exhibiting type-2 layers. Understanding the differences in metrics between the two observed layer topologies can be achieved through inspection of D

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

cations. The parallel orientations of these organic cations with respect to the [(VO)2(C2O4)(SeO3)2]n2n− layers preclude any one ammonium center from donating multiple hydrogen bonds to the same inorganic layer. As such, occluded water molecules are incorporated into the structures to satisfy the hydrogenbonding preferences of these cations. The SBUs from which compounds 1−8b and [C4H12N2][(VO)2(C2O4)(SeO3)2] are constructed differ only in the orientations of the [SeO3] groups. Adjacent [SeO3] groups are anti-aligned in both the type-1 and the type-2 layers, in order to minimize steric interactions between lone pairs. See Figure 2. In addition, the stereoactive lone pairs are generally buried within the inorganic layers in 1−8b, because the inter-layer space is filled by the organic cations and occluded water molecules. See Figure 3. Initial inspection of [C4H12N2][(VO)2(C2O4)(SeO3)2]22 appears to contradict the trends articulated above. The [pipH2]2+ cations are smaller than any of the organic cations in 1−8b, yet [C4H12N2][(VO)2(C2O4)(SeO3)2] exhibits the “expanded” type-1 layer topology. Additionally, each [pipH2]2+ contains two secondary ammonium cations, yet no occluded water molecules are found in this compound. However, the principles that govern the formation of compounds 1−8b also apply to [C4H12N2][(VO)2(C2O4)(SeO3)2]. The organic amines in 1−8b are forced to lie parallel to planes of layer propagation owing to steric effects. In contrast, the [pipH2]2+ cations are able to orient perpendicularly to the inorganic layers. See Figure 3c. This enables each secondary ammonium cation on every [pipH2]2+ to donate both of its N−H···O hydrogen bonds to the same [(VO)2(C2O4)(SeO3)2]n2n− layer. The pores in the type-1 layers are large enough to accommodate the [pipH2]2+ cations, whereas those in the type-2 layers are too small. See Figure 5. As such, the “expanded” type-1 layers are observed in [C4H12N2][(VO)2(C2O4)(SeO3)2].

their respective connectivities and inter-atom separation distances. Both high-density and low-density layers can be formed from the SBUs, depending upon the relative packing densities of the organic cations in the interlayer spacings. Specifically, the “expanded” type-1 layers contain larger pores constructed from two [SeO3], two [VO6] polyhedra, and two oxalate bridges. See Figure 4a. In contrast, the pores in the

Figure 4. Ball-and-stick representations of the (a) type-1 layers in 1 and (b) type-2 layers in 6. Green, purple, red and white spheres represent vanadium, selenium, oxygen and carbon atoms, respectively. ELF isosurfaces are shown with a boundary condition of 0.96. Selected bond lengths are included.

Figure 5. Hydrogen-bonding interactions in [C4H12N2][(VO)2(C2O4)(SeO3)]. Green octahedra represent [VO6], while purple, red, blue, and white spheres represent selenium, oxygen, nitrogen, and carbon atoms, respectively. ELF isosurfaces are shown with a boundary condition of 0.96. Hydrogen atoms have been removed for clarity. Hydrogenbonding interactions are shown as dashed lines.

“contracted” type-2 layers are constructed from two [SeO3] and two [VO6] polyhedra and just one oxalate bridge. See Figure 4b. Se···Se separation distances are longer in type-1 layers (3.704(3), 4.563(3), and 6.360(3) Å) versus type-2 layers (3.487(3), 3.704(3), and 5.373(3) Å). The presence or absence of occluded water molecules in these compounds does not affect the relationship between ammonium cation size and layer topology. Instead, the inclusion of water is dictated by hydrogen-bonding interactions. The [1,4dmpipH2]2+ and [tmedH2]2+ cations in 1 and 4, respectively, contain only tertiary ammonium centers, which each donate a single N−H···O bond to the adjacent layers. All other organic cations in these compounds contain some secondary ammonium

Potential inter-layer void space caused by the perpendicular orientations of the [pipH2]2+ in [C4H12N2][(VO)2(C2O4)(SeO3)2] is minimized by changes in the orientations of the [SeO3] groups. Specifically, the stereoactive lone pairs in all [SeO3] groups in 1−8b are independent of layer topology and are largely buried within the inorganic layers. See Figure 3a,b. In contrast, the stereoactive lone pairs in [C4H12N2][(VO)2(C 2 O 4 )(SeO 3 ) 2 ] occupy the inter-layer space between [pipH2]2+ cations. See Figure 3c. In addition, the separation E

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

Table 3. Calculated Dipole Moments in [(R)-C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (8a) and [(S)C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (8b) [(R)-C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (8a)

[(S)-C5H14N2][(VO)2(C2O4)(SeO3)2]·2H2O (8b)

species

dipole moment (D)

species

dipole moment (D)

V(1)O6 V(2)O6 Se(1)O3 Se(2)O3 oxalate [(R)-2-mpipH2]2+ H2O(13) H2O(14) [(VO)2(C2O4)(SeO2)2]n2n− layer net moment

8.57 8.27 8.70 8.83 0.14 2.38 2.52 2.56 0.31 2.36

V(1)O6 V(2)O6 Se(1)O3 Se(2)O3 oxalate [(S)-2-mpipH2]2+ H2O(13) H2O(14) [(VO)2(C2O4)(SeO2)2]n2n− layer net moment

8.38 8.50 8.81 8.76 0.34 2.81 2.54 2.55 0.79 0.65

Figure 6. Ball-and-stick representation of (a) 8a and (b) 8b. Arrows indicate the approximate directions and magnitudes of the dipole moments for the [VO6] and [SeO3] polyhedral, water molecules, and [(R)-2-mpipH2]2+ and [(S)-2-mpipH2]2+ cations. The large black arrows represent the direction of the net dipole moments for 8a and 8b. Organic ammonium cation hydrogen atoms have been removed for clarity.

orientations in [C4H12N2][(VO)2(C2O4)(SeO3)2] with respect to the other type-1 layer compounds (1−5) is also shown in Figure 1a,b.

distance between inorganic layers in [C4H12N2][(VO)2(C2O4)(SeO3)2] is significantly shorter (6.823(8) Å) than in 1−8b (7.840(2)−9.086(3) Å). The difference in the [SeO 3 ] F

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

SBUs in 8a/8b; powder XRD; and tables with bond valence sums and Hirshfeld-I partial atomic charges. An X-ray crystallographic information file (CIF) is available for 1−7 and 8a/8b. This material is available free of charge via the Internet at http://pubs. acs.org.

The use of chiral components to force crystallographic noncentrosymmetry has been established in a range of systems.14,15,19−21,39−43 This technique was explored by the use of both racemic and enantiomerically pure sources of (R)-2-methylpiperazine and (S)-2-methylpiperazine. Compound 7 contains a racemic mixture of [(R)-2-mpipH2]2+ and [(S)-2-mpipH2]2+ and crystallizes in the centrosymmetric space group P21/c (No. 14). Both [(R)-2-mpipH2]2+ and [(S)-2-mpipH2]2+ are disordered over the same site, with 50% occupancy of the methyl groups. A figure detailing this disorder mechanism is available in the Supporting Information. Compound 8a only contains [(R)-2mpipH2]2+, whereas 8b only contains [(S)-2-mpipH2]2+. These two structures constitute an enantiomeric pair, with each being the approximate inverse of the other. 8a and 8b both crystallize in the noncentrosymmetric space group P21 (No. 4). The magnitudes and directions of both component and net dipole moments were calculated for 8a and 8b, using a method reported earlier14,15,19,44−46 in which the Hirshfeld-I scheme30,31,47 was used to determine partial atomic charges. Dipole moments were calculated for each [VO6] and [SeO3] coordination polyhedra, in addition to the H2O molecules, oxalate bridges, and [(R)-2-mpipH2]2+ and [(S)-2-mpipH2]2+ cations. Calculated component and net dipole moments are listed in Table 3 and are shown in Figure 6. The effects of pseudoinversion within the [(VO)2(C2O4)(SeO3)2]n2n− layers are clearly evident. The component moments of the [V(1)O6]/[V(2)O6] and [Se(1)O3]/[Se(2)O3] are essentially anti-aligned. The dipole moments on the [(R)-2-mpipH2]2+ and [(S)-2-mpipH2]2+ cations both contain small components along the b axis, which result in a small net dipole moment for the organic cations. Far less cancellation of the dipole moments on the water molecules is observed, and they are responsible for the largest contributions to the net dipole moments of 8a and 8b. The small differences in calculated dipole moments of related sites in 8a and 8b are caused by the asymmetric charge distribution on the [(R)-2-mpipH2]2+ and [(S)-2-mpipH2]2+ cations. Such small differences have been observed in other vanadium selenites.15 Elucidating the principles that govern the formation of new solid-state compounds is critically important for the directed synthesis of new materials. The form of the SBUs present in 1− 8b and [C4H12N2][(VO)2(C2O4)(SeO3)2] is largely dictated by the composition of the reaction gel, while the manner in which the SBUs come together to form periodic solids is dependent upon the structure of the organic ammonium cations. Specifically, the three-dimensional structures of these templated vanadium selenite oxalates maximize the strengths of the hydrogen-bonding networks while minimizing void space between inorganic layers. The presence of only two different [(VO)2(C2O4)(SeO3)2]n2n− layer topologies is caused by the connectivity of the SBUs from which the layers are constructed. The same principles that govern the formation of compounds 1−8b and [C4H12N2][(VO)2(C2O4)(SeO3)2] directly affect the formation of many other amine-templated oxides. The composition of the reaction mixture largely dictates the form of the inorganic building units, which, in turn, restrict the topologies of the inorganic components.48−50 Hydrogen-bonding between the organic donor cations and inorganic acceptor anions directs the infinite condensation of the respective building units.33

■

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel: (610) 896 2949. Fax: (610) 896 4963. http://www.haverford.edu/chem/Norquist/. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The authors acknowledge support from the NSF (Award No. CHE-0911121), the Henry Dreyfus Teacher-Scholar Awards Program, and grants to Haverford College from the HHMI Undergraduate Science Education Program. M.Z. acknowledges support for the purchase of a diffractometer from the NSF grant 0087210, the Ohio Board of Regents grant CAP-491, and from Youngstown State University. The authors also thank the NSF (Award No. CHE-1039689) for funding ISU’s X-ray diffractometer. This research used resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number OCI-1053575.

■

REFERENCES

(1) Julve, M.; Verdaguer, M.; Gleizes, A.; Philoche-Levisalles, M.; Kahn, O. Inorg. Chem. 1984, 23, 3808. (2) Clemente-Leon, M.; Coronado, E.; Marti-Gastaldo, C.; Romero, F. M. Chem. Soc. Rev. 2011, 40, 473. (3) Nagarathinam, M.; Saravanan, K.; Phua, E. J. H.; Reddy, M. V.; Chowdari, B. V. R.; Vittal, J. J. Angew. Chem., Int. Ed. 2012, 51, 5866. (4) Adamson, A. W.; Waltz, W. L.; Zinato, E.; Watts, D. W.; Fleischauer, P. D.; Lindholm, R. D. Chem. Rev. 1968, 68, 541. (5) Marinescu, G.; Andruh, M.; Lloret, F.; Julve, M. Coord. Chem. Rev. 2011, 255, 161. (6) Weng, S.-F.; Wang, Y.-H.; Lee, C.-S. J. Solid State Chem. 2012, 188, 77. (7) Calahorro, A. J.; Fairen-Jimenez, D.; Salinas-Castillo, A.; LopezViseras, M. E.; Rodriguez-Dieguez, A. Polyhedron 2013, 52, 315. (8) Gu, Z.-G.; Fang, H.-C.; Yin, P.-Y.; Tong, L.; Ying, Y.; Hu, S.-J.; Li, W.-S.; Cai, Y.-P. Cryst. Growth Des. 2011, 11, 2220. (9) Ma, L.; Peng, G.; Cai, J.-B.; Deng, H. Z. Anorg. Allg. Chem. 2011, 637, 2278. (10) Wang, H.; Liu, S.-J.; Tian, D.; Jia, J.-M.; Hu, T.-L. Cryst. Growth Des. 2012, 12, 3263. (11) Sadakiyo, M.; Yamada, T.; Kitagawa, H. J. Am. Chem. Soc. 2011, 133, 11050. (12) Sadakiyo, M.; Yamada, T.; Kitagawa, H. J. Am. Chem. Soc. 2009, 131, 9906. (13) Yeon, J.; Kim, S.-H.; Nguyen, S. D.; Lee, H.; Halasyamani, P. S. Inorg. Chem. 2012, 51, 609. (14) Smith, M. D.; Blau, S. M.; Chang, K. B.; Tran, T. T.; Zeller, M.; Halasyamani, P. S.; Schrier, J.; Norquist, A. J. J. Solid State Chem. 2012, 195, 86. (15) Olshansky, J. H.; Thao Tran, T.; Hernandez, K. J.; Zeller, M.; Halasyamani, P. S.; Schrier, J.; Norquist, A. J. Inorg. Chem. 2012, 51, 11040. (16) Yeon, J.; Kim, S.-H.; Nguyen, S. D.; Lee, H.; Halasyamani, P. S. Inorg. Chem. 2012, 51, 2662.

ASSOCIATED CONTENT

S Supporting Information *

Packing views for all compounds; figures showing disorder mechanisms for 3, 5, and 7; ball-and-stick representation of the G

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

(17) Lee, D. W.; Oh, S.-J.; Halasyamani, P. S.; Ok, K. M. Inorg. Chem. 2011, 50, 4473. (18) Yeon, J.; Kim, S.-H.; Halasyamani, P. S. Inorg. Chem. 2010, 49, 6986. (19) Glor, E. C.; Blau, S. M.; Yeon, J.; Zeller, M.; Shiv Halasyamani, P.; Schrier, J.; Norquist, A. J. J. Solid State Chem. 2011, 184, 1445. (20) Veltman, T. R.; Stover, A. K.; Narducci Sarjeant, A.; Ok, K. M.; Halasyamani, P. S.; Norquist, A. J. Inorg. Chem. 2006, 45, 5529. (21) Muller, E. A.; Cannon, R. J.; Narducci Sarjeant, A.; Ok, K. M.; Halasyamani, P. S.; Norquist, A. J. Cryst. Growth Des. 2005, 5, 1913. (22) Lian, Z.; Zhang, J.; Gu, Y.; Wang, T.; Lou, T. J. Mol. Struct. 2009, 919, 122. (23) APEX2; Bruker AXS Inc.: Madison, WI, 2009. (24) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl. Crystallogr. 1993, 26, 343. (25) Betteridge, P. W.; Carruthers, J. R.; Cooper, R. I.; Prout, K.; Watkin, D. J. J. Appl. Crystallogr. 2003, 36, 1487. (26) Dowty, E. ATOMS v.6.0; Shape Software: Kingsport, TN, 2002. (27) Gonze, X.; Beuken, J. M.; Caracas, R.; Detraux, F.; Fuchs, M.; Rignanese, G. M.; Sindic, L.; Verstraete, M.; Zerah, G.; Jollet, F.; Torrent, M.; Roy, A.; Mikami, M.; Ghosez, P.; Raty, J. Y.; Allan, D. C. Comput. Mater. Sci. 2002, 25, 478. (28) Gonze, X.; Amadon, B.; Anglade, P. M.; Beuken, J. M.; Bottin, F.; Boulanger, P.; Bruneval, F.; Caliste, D.; Caracas, R.; Cote, M.; Deutsch, T.; Genovese, L.; Ghosez, P.; Giantomassi, M.; Goedecker, S.; Hamann, D. R.; Hermet, P.; Jollet, F.; Jomard, G.; Leroux, S.; Mancini, M.; Mazevet, S.; Oliveira, M. J. T.; Onida, G.; Pouillon, Y.; Rangel, T.; Rignanese, G. M.; Sangalli, D.; Shaltaf, R.; Torrent, M.; Verstraete, M. J.; Zerah, G.; Zwanziger, J. W. Comput. Phys. Commun. 2009, 180, 2582. (29) Momma, K.; Izumi, F. J. Appl. Crystallogr. 2008, 41, 653. (30) Bultinck, P.; Van Alsenoy, C.; Ayers, P. W.; Carbo-Dorca, R. J. Chem. Phys. 2007, 126, 144111. (31) Bultinck, P.; Ayers, P. W.; Fias, S.; Tiels, K.; Van Alsenoy, C. Chem. Phys. Lett. 2007, 444, 205. (32) Gaigalas, G.; Froese Fischer, C. Comput. Phys. Commun. 1996, 98, 255. (33) Smith, M. D.; Blau, S. M.; Chang, K. B.; Zeller, M.; Schrier, J.; Norquist, A. J. Cryst. Growth Des. 2011, 11, 4213. (34) Chang, K. B.; Smith, M. D.; Blau, S. M.; Glor, E. C.; Zeller, M.; Schrier, J.; Norquist, A. J. Cryst. Growth Des. 2013, 13, 2190. (35) Brown, I. D.; Altermatt, D. Acta Crystallogr., Sect. B 1985, 41, 244. (36) Brese, N. E.; O’Keeffe, M. Acta Crystallogr., Sect. B 1991, 47, 192. (37) Do, J.; Bontchev, R. P.; Jacobson, A. J. Inorg. Chem. 2000, 39, 3230. (38) Lin, H.-M.; Lii, K.-H.; Jiang, Y.-C.; Wang, S.-L. Chem. Mater. 1999, 11, 519. (39) Kepert, C. J.; Prior, T. J.; Rosseinsky, M. J. J. Am. Chem. Soc. 2000, 122, 5158. (40) Inoue, M.; Yamase, T. Bull. Chem. Soc. Jpn. 1995, 68, 3055. (41) Gutnick, J. R.; Muller, E. A.; Narducci Sarjeant, A.; Norquist, A. J. Inorg. Chem. 2004, 43, 6528. (42) Hubbard, D. J.; Johnston, A. R.; Sanchez Casalongue, H.; Narducci Sarjeant, A.; Norquist, A. J. Inorg. Chem. 2008, 47, 8518. (43) Choyke, S. J.; Blau, S. M.; Larner, A. A.; Narducci Sarjeant, A.; Yeon, J.; Halasyamani, P. S.; Norquist, A. J. Inorg. Chem. 2009, 48, 11277. (44) Kim, J.-H.; Baek, J.; Halasyamani, P. S. Chem. Mater. 2007, 19, 5637. (45) Maggard, P. A.; Nault, T. S.; Stern, C. L.; Poeppelmeier, K. R. J. Solid State Chem. 2003, 175, 27. (46) Izumi, H. K.; Kirsch, J. E.; Stern, C. L.; Poeppelmeier, K. R. Inorg. Chem. 2005, 44, 884. (47) Van Damme, S.; Bultinck, P.; Fias, S. J. Chem. Theory Comput. 2009, 5, 334. (48) Ferey, G. Chem. Mater. 2001, 13, 3084. (49) Chang, K. B.; Hubbard, D. J.; Zeller, M.; Schrier, J.; Norquist, A. J. Inorg. Chem. 2010, 49, 5167. (50) Casalongue, H. S.; Choyke, S. J.; Narducci Sarjeant, A.; Schrier, J.; Norquist, A. J. J. Solid State Chem. 2009, 182, 1297. H

dx.doi.org/10.1021/cg400992q | Cryst. Growth Des. XXXX, XXX, XXX−XXX