research communications
H-imidazol-3-ium) μ-oxalato-bis[n-butyltrichloridostannate(IV)]
of bis(2-methyl-1aLaboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal, and bDepartment of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46557-5670, USA
*Correspondence e-mail: mouhamadoubdiop@gmail.com
The SnIV atom in the centrosymmetric anion of the title salt, (C4H7N2)2[Sn2(C4H9)2(C2O4)Cl6], is coordinated in a distorted octahedral mode by two O atoms of a bridging oxalate moiety, three Cl atoms and a C atom of an n-butyl group. The latter is disordered over two sets of sites in a 0.66:0.33 occupancy ratio. N—H⋯O and N—H⋯Cl hydrogen bonds involving the 2-methylimidazolium cation and neighbouring anions result in the formation of chains extending parallel to [001].
Keywords: crystal structure; organotin(IV) complex; oxalate; hydrogen bonds.
CCDC reference: 1481678
1. Chemical context
Ammonium salts of oxalatostannates(IV) with additional halogen atoms bonded within the anion are well known in the literature. Skapski et al. (1974) have reported the of [(R4N)2][C2O4(SnCl4)2] (R = ethyl) while Le Floch et al. (1975) have published spectroscopic studies of [(R4N)2][C2O4(SnX4)2] (R = ethyl, X = Cl, Br, I; R = butyl, X = Br). Our group has investigated several complexes containing an oxalate group chelating an SnCl4 moiety or an [SnCl3·H2O]+ fragment, resulting in framework structures (Sow et al., 2013; Diop et al., 2015). In all cases, the environment around the tin(IV) atom is distorted octahedral.
In the present communication we report on the reaction between 2-methyl-imidazolium hydrogenoxalate dihydrate and tin(IV) butyltrichloride that yielded the title compound, (C4H7N2)2[(Sn2(C4H9)2(C2O4)Cl6].
2. Structural commentary
The distannate anion, [Sn2(C4H9)2(C2O4)Cl6]2−, is located about a center of symmetry and thus only one half of the molecule is present in the (Fig. 1). The full molecule consists of a central oxalate anion bridging two SnBuCl3 moieties (Fig. 2) similar to the binuclear stannate(IV) anion reported for (Et4N)2[C2O4(SnCl4)2] (Skapski et al., 1974). In addition to the bis-chelating and bridging oxalate oxygen atoms, the octahedral coordination sphere is completed by three chlorine atoms and the C atom of a disordered n-butyl group (Fig. 1). The C—O distances (Table 1) are consistent with an almost perfect π delocalization within the oxalate anion, as expected for a centrosymmetric bis-chelation. The Sn—C length is consistent with previously reported values (Table 1; Diop et al., 2013). The Sn—Cl distances (Table 1) are also comparable with those in related compounds, e.g. in (Bu4N)[SnBuCl4] (Diop et al., 2013), (Me4N)[C2O4SnCl3(H2O)] (Sow et al., 2013) or [(methyl-2-imidazolium)][C2O4SnCl3(H2O)] (Diop et al., 2015). The equatorial Sn—Cl1 bond that is coplanar with the oxalate anion is considerably shorter than the Sn—Cl2 and Sn—Cl3 bonds that are oriented axially (Fig. 2, Table 1). The Sn—O1 and Sn—O2 bond lengths are fully consistent with previously characterized examples (Sow et al., 2013; Gueye et al., 2014; Sarr et al., 2015). Distortions from an ideal octahedral coordination environment are reflected in the bond angles about the SnIV atom (Table 1). Notably, the O1—Sn—O2 angle is less than 90° and the axial Cl2—Sn—Cl3 bond angle deviates considerably from an ideal of 180°.
One methyl-2-imidazolium counter-cation is also present in the π-delocalization in this cation (Table 1).
As expected, the lengths of the C—N and C7—C8 bonds indicate3. Supramolecular features
The imidazolium cation bridges two neighbouring [Sn2(C4H9)2(C2O4)Cl6]2− anions through N—H⋯O and N—H⋯Cl hydrogen bonds, leading to the formation of chains extending parallel to [001] (Fig. 3, Table 2) whereby pairs of the cations are involved in this bridging motif, each alternating across the inversion center located between the cations. The chains are connected by additional C—H⋯Cl hydrogen bonds, giving a layer structure parallel to (100).
4. Database survey
A search of the Cambridge Structural Database (Version 5.37 with one update; Groom et al., 2016) returned 51 different structures containing 2-methyl-1H-imidazol-3-ium cations and hundreds of those containing bis-chelating oxalate anions. Those of particular relevance to the title structure have been detailed above.
5. Synthesis and crystallization
Crystals of [2-methyl-1H-imidazol-3-ium][HC2O4·2H2O] (L) were obtained by mixing equimolar amounts of 2-methyl-imidazole with oxalic acid in water, followed by forced evaporation of the solvent at 333 K. A molar 2:1 mixture of (L) with SnBuCl3 in acetonitrile was allowed to react. Crystals of the title compound suitable for structural examination were obtained after slow evaporation of acetonitrile at room temperature.
6. Refinement
Crystal data, data collection and structure . Hydrogen atoms were included in geometrically calculated positions with C—H = 0.98 (methyl) and 0.99 Å (methylene), with Uiso(H) = 1.5Ueq(C) (methyl), and 1.2Ueq(C) (methylene). H atoms bound to N atoms within the cation were derived from difference maps and were refined freely. The n-butyl group was found to exhibit positional disorder, and was modelled with the peripheral three carbon atoms disordered over two sets of sites. Occupancies for these two sets were initially refined upon inspection of the refined occupancies. In the final model the occupancies were fixed at 2/3:1/3. Disordered pairs of carbon atoms (C3/C3A, C4/C4A, C5/C5A) were restrained to have similar atomic displacement parameters.
details are summarized in Table 3
|
Supporting information
CCDC reference: 1481678
https://doi.org/10.1107/S2056989016008434/wm5293sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016008434/wm5293Isup2.hkl
Data collection: APEX2 (Bruker, 2015); cell
SAINT (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: XP (Sheldrick, 2008); software used to prepare material for publication: CIFTAB (Sheldrick, 2008) and publCIF (Westrip, 2010).(C4H7N2)2[Sn2(C4H9)2(C2O4)Cl6] | F(000) = 804 |
Mr = 818.60 | Dx = 1.754 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 13.4674 (5) Å | Cell parameters from 9885 reflections |
b = 11.4709 (4) Å | θ = 2.7–28.3° |
c = 10.2030 (3) Å | µ = 2.16 mm−1 |
β = 100.453 (1)° | T = 200 K |
V = 1550.03 (9) Å3 | Block, colorless |
Z = 2 | 0.29 × 0.18 × 0.12 mm |
Bruker Kappa X8 APEXII diffractometer | 3868 independent reflections |
Radiation source: fine-focus sealed tube | 3490 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
Detector resolution: 8.33 pixels mm-1 | θmax = 28.3°, θmin = 2.4° |
combination of ω and φ–scans | h = −17→13 |
Absorption correction: numerical (SADABS; Krause et al., 2015) | k = −14→15 |
Tmin = 0.671, Tmax = 0.811 | l = −13→13 |
20211 measured reflections |
Refinement on F2 | Primary atom site location: real-space vector search |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.021 | Hydrogen site location: mixed |
wR(F2) = 0.051 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0236P)2 + 0.9516P] where P = (Fo2 + 2Fc2)/3 |
3868 reflections | (Δ/σ)max = 0.022 |
192 parameters | Δρmax = 0.69 e Å−3 |
18 restraints | Δρmin = −0.46 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Disorder in the n-butyl chain was modeled over two sites. Occupancies were initially refined and subsequently set to 0.66667:0.33333. Carbon atoms were refined with anisotropic atomic displacement parameters and the disordered carbon atoms were restrained to have similar displacement parameters. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Sn1 | 0.71591 (2) | 0.52312 (2) | 0.53372 (2) | 0.03131 (5) | |
Cl1 | 0.81275 (4) | 0.42161 (6) | 0.39795 (5) | 0.04767 (13) | |
Cl2 | 0.71227 (4) | 0.35142 (5) | 0.67619 (5) | 0.04538 (12) | |
Cl3 | 0.66628 (5) | 0.67332 (6) | 0.36433 (6) | 0.05395 (15) | |
O1 | 0.58579 (10) | 0.43651 (13) | 0.41329 (12) | 0.0341 (3) | |
O2 | 0.41920 (10) | 0.42053 (12) | 0.38137 (13) | 0.0339 (3) | |
C1 | 0.50131 (14) | 0.45924 (16) | 0.44091 (17) | 0.0296 (4) | |
C2 | 0.81592 (17) | 0.6238 (2) | 0.6744 (2) | 0.0465 (5) | |
H2A | 0.7753 | 0.6723 | 0.7251 | 0.056* | 0.6667 |
H2B | 0.8569 | 0.5700 | 0.7383 | 0.056* | 0.6667 |
H2C | 0.7810 | 0.6968 | 0.6911 | 0.056* | 0.3333 |
H2D | 0.8300 | 0.5800 | 0.7594 | 0.056* | 0.3333 |
C3 | 0.8844 (5) | 0.7002 (5) | 0.6182 (8) | 0.0621 (16) | 0.6667 |
H3A | 0.8439 | 0.7537 | 0.5534 | 0.075* | 0.6667 |
H3B | 0.9263 | 0.6520 | 0.5689 | 0.075* | 0.6667 |
C4 | 0.9514 (6) | 0.7697 (7) | 0.7186 (9) | 0.096 (3) | 0.6667 |
H4A | 0.9091 | 0.8112 | 0.7734 | 0.115* | 0.6667 |
H4B | 0.9955 | 0.7154 | 0.7783 | 0.115* | 0.6667 |
C5 | 1.0148 (5) | 0.8544 (6) | 0.6693 (11) | 0.147 (4) | 0.6667 |
H5A | 1.0609 | 0.8144 | 0.6202 | 0.221* | 0.6667 |
H5B | 1.0539 | 0.8973 | 0.7444 | 0.221* | 0.6667 |
H5C | 0.9725 | 0.9090 | 0.6097 | 0.221* | 0.6667 |
C3A | 0.9164 (10) | 0.6557 (15) | 0.6353 (18) | 0.089 (5) | 0.3333 |
H3C | 0.9050 | 0.7118 | 0.5603 | 0.107* | 0.3333 |
H3D | 0.9483 | 0.5850 | 0.6057 | 0.107* | 0.3333 |
C4A | 0.9967 (9) | 0.7180 (13) | 0.772 (2) | 0.125 (6) | 0.3333 |
H4C | 0.9875 | 0.6829 | 0.8578 | 0.150* | 0.3333 |
H4D | 1.0686 | 0.7138 | 0.7634 | 0.150* | 0.3333 |
C5A | 0.9606 (11) | 0.8257 (19) | 0.7572 (18) | 0.115 (5) | 0.3333 |
H5D | 1.0101 | 0.8801 | 0.8061 | 0.173* | 0.3333 |
H5E | 0.8976 | 0.8304 | 0.7921 | 0.173* | 0.3333 |
H5F | 0.9476 | 0.8462 | 0.6624 | 0.173* | 0.3333 |
N1 | 0.61980 (17) | 0.41626 (18) | 0.13231 (19) | 0.0462 (5) | |
H1N | 0.644 (2) | 0.434 (3) | 0.201 (3) | 0.059 (9)* | |
N2 | 0.60535 (16) | 0.37133 (18) | −0.07045 (18) | 0.0463 (5) | |
H2N | 0.6237 (19) | 0.366 (2) | −0.137 (2) | 0.044 (7)* | |
C6 | 0.6683 (2) | 0.4165 (2) | 0.0316 (2) | 0.0487 (5) | |
C7 | 0.52646 (18) | 0.36986 (19) | 0.0958 (2) | 0.0438 (5) | |
H7 | 0.4773 | 0.3595 | 0.1508 | 0.053* | |
C8 | 0.51718 (18) | 0.34151 (19) | −0.0328 (2) | 0.0438 (5) | |
H8A | 0.4600 | 0.3072 | −0.0873 | 0.053* | |
C9 | 0.7714 (3) | 0.4571 (4) | 0.0320 (3) | 0.0894 (12) | |
H9A | 0.7993 | 0.4905 | 0.1193 | 0.134* | |
H9B | 0.7707 | 0.5166 | −0.0370 | 0.134* | |
H9C | 0.8134 | 0.3913 | 0.0140 | 0.134* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sn1 | 0.02611 (7) | 0.04132 (8) | 0.02698 (7) | −0.00213 (5) | 0.00611 (5) | −0.00174 (5) |
Cl1 | 0.0358 (3) | 0.0706 (4) | 0.0385 (3) | 0.0073 (2) | 0.0116 (2) | −0.0100 (2) |
Cl2 | 0.0549 (3) | 0.0459 (3) | 0.0359 (2) | −0.0024 (2) | 0.0097 (2) | 0.0052 (2) |
Cl3 | 0.0489 (3) | 0.0611 (4) | 0.0522 (3) | 0.0034 (3) | 0.0101 (3) | 0.0221 (3) |
O1 | 0.0282 (7) | 0.0459 (7) | 0.0289 (6) | −0.0013 (6) | 0.0074 (5) | −0.0078 (6) |
O2 | 0.0286 (7) | 0.0432 (8) | 0.0304 (6) | −0.0032 (6) | 0.0065 (5) | −0.0085 (6) |
C1 | 0.0300 (9) | 0.0354 (9) | 0.0243 (8) | −0.0013 (7) | 0.0073 (7) | −0.0005 (7) |
C2 | 0.0365 (11) | 0.0579 (14) | 0.0445 (11) | −0.0075 (10) | 0.0058 (9) | −0.0150 (10) |
C3 | 0.045 (3) | 0.059 (3) | 0.078 (3) | −0.020 (2) | 0.000 (3) | 0.002 (3) |
C4 | 0.077 (5) | 0.080 (5) | 0.121 (6) | −0.043 (4) | −0.009 (4) | −0.041 (4) |
C5 | 0.061 (4) | 0.082 (4) | 0.283 (12) | −0.032 (3) | −0.009 (5) | −0.007 (6) |
C3A | 0.050 (8) | 0.110 (13) | 0.111 (12) | −0.031 (7) | 0.024 (7) | −0.061 (10) |
C4A | 0.053 (7) | 0.094 (10) | 0.233 (19) | 0.011 (6) | 0.042 (9) | −0.020 (11) |
C5A | 0.058 (8) | 0.169 (18) | 0.122 (13) | −0.011 (10) | 0.027 (8) | −0.018 (12) |
N1 | 0.0598 (13) | 0.0507 (11) | 0.0279 (9) | −0.0053 (9) | 0.0073 (8) | −0.0023 (8) |
N2 | 0.0590 (12) | 0.0515 (11) | 0.0290 (9) | −0.0022 (9) | 0.0097 (8) | −0.0031 (8) |
C6 | 0.0551 (14) | 0.0579 (14) | 0.0330 (10) | −0.0088 (11) | 0.0080 (9) | 0.0010 (9) |
C7 | 0.0513 (13) | 0.0393 (11) | 0.0425 (11) | 0.0014 (9) | 0.0132 (10) | 0.0031 (9) |
C8 | 0.0495 (12) | 0.0363 (10) | 0.0443 (11) | −0.0019 (9) | 0.0050 (10) | −0.0012 (9) |
C9 | 0.063 (2) | 0.153 (4) | 0.0526 (17) | −0.038 (2) | 0.0123 (14) | −0.0002 (19) |
Sn1—C2 | 2.122 (2) | C5—H5C | 0.9800 |
Sn1—O1 | 2.1878 (13) | C3A—C4A | 1.76 (2) |
Sn1—O2i | 2.2475 (13) | C3A—H3C | 0.9900 |
Sn1—Cl1 | 2.3731 (5) | C3A—H3D | 0.9900 |
Sn1—Cl3 | 2.4460 (6) | C4A—C5A | 1.33 (2) |
Sn1—Cl2 | 2.4536 (5) | C4A—H4C | 0.9900 |
O1—C1 | 1.248 (2) | C4A—H4D | 0.9900 |
O2—C1 | 1.243 (2) | C5A—H5D | 0.9800 |
O2—Sn1i | 2.2475 (13) | C5A—H5E | 0.9800 |
C1—C1i | 1.531 (3) | C5A—H5F | 0.9800 |
C2—C3 | 1.463 (7) | N1—C6 | 1.313 (3) |
C2—C3A | 1.524 (16) | N1—C7 | 1.354 (3) |
C2—H2A | 0.9900 | N1—H1N | 0.74 (3) |
C2—H2B | 0.9900 | N2—C6 | 1.323 (3) |
C2—H2C | 0.9900 | N2—C8 | 1.356 (3) |
C2—H2D | 0.9900 | N2—H2N | 0.77 (2) |
C3—C4 | 1.471 (9) | C6—C9 | 1.465 (4) |
C3—H3A | 0.9900 | C7—C8 | 1.336 (3) |
C3—H3B | 0.9900 | C7—H7 | 0.9500 |
C4—C5 | 1.443 (11) | C8—H8A | 0.9500 |
C4—H4A | 0.9900 | C9—H9A | 0.9800 |
C4—H4B | 0.9900 | C9—H9B | 0.9800 |
C5—H5A | 0.9800 | C9—H9C | 0.9800 |
C5—H5B | 0.9800 | ||
C2—Sn1—O1 | 166.44 (7) | C4—C5—H5B | 109.5 |
C2—Sn1—O2i | 92.40 (7) | H5A—C5—H5B | 109.5 |
O1—Sn1—O2i | 74.04 (5) | C4—C5—H5C | 109.5 |
C2—Sn1—Cl1 | 108.24 (6) | H5A—C5—H5C | 109.5 |
O1—Sn1—Cl1 | 85.32 (4) | H5B—C5—H5C | 109.5 |
O2i—Sn1—Cl1 | 159.27 (4) | C2—C3A—C4A | 109.7 (11) |
C2—Sn1—Cl3 | 98.81 (7) | C2—C3A—H3C | 109.7 |
O1—Sn1—Cl3 | 80.48 (4) | C4A—C3A—H3C | 109.7 |
O2i—Sn1—Cl3 | 86.17 (4) | C2—C3A—H3D | 109.7 |
Cl1—Sn1—Cl3 | 92.40 (2) | C4A—C3A—H3D | 109.7 |
C2—Sn1—Cl2 | 96.58 (7) | H3C—C3A—H3D | 108.2 |
O1—Sn1—Cl2 | 82.42 (4) | C5A—C4A—C3A | 97.3 (16) |
O2i—Sn1—Cl2 | 84.14 (4) | C5A—C4A—H4C | 112.3 |
Cl1—Sn1—Cl2 | 91.38 (2) | C3A—C4A—H4C | 112.3 |
Cl3—Sn1—Cl2 | 162.13 (2) | C5A—C4A—H4D | 112.3 |
C1—O1—Sn1 | 116.64 (12) | C3A—C4A—H4D | 112.3 |
C1—O2—Sn1i | 114.80 (11) | H4C—C4A—H4D | 109.9 |
O2—C1—O1 | 125.55 (17) | C4A—C5A—H5D | 109.5 |
O2—C1—C1i | 117.2 (2) | C4A—C5A—H5E | 109.5 |
O1—C1—C1i | 117.2 (2) | H5D—C5A—H5E | 109.5 |
C3—C2—Sn1 | 115.4 (3) | C4A—C5A—H5F | 109.5 |
C3A—C2—Sn1 | 116.0 (6) | H5D—C5A—H5F | 109.5 |
C3—C2—H2A | 108.4 | H5E—C5A—H5F | 109.5 |
Sn1—C2—H2A | 108.4 | C6—N1—C7 | 110.7 (2) |
C3—C2—H2B | 108.4 | C6—N1—H1N | 122 (2) |
Sn1—C2—H2B | 108.4 | C7—N1—H1N | 126 (2) |
H2A—C2—H2B | 107.5 | C6—N2—C8 | 110.15 (19) |
C3A—C2—H2C | 108.3 | C6—N2—H2N | 117.8 (19) |
Sn1—C2—H2C | 108.3 | C8—N2—H2N | 132.1 (19) |
C3A—C2—H2D | 108.3 | N1—C6—N2 | 106.0 (2) |
Sn1—C2—H2D | 108.3 | N1—C6—C9 | 127.2 (2) |
H2C—C2—H2D | 107.4 | N2—C6—C9 | 126.7 (2) |
C2—C3—C4 | 113.7 (6) | C8—C7—N1 | 106.4 (2) |
C2—C3—H3A | 108.8 | C8—C7—H7 | 126.8 |
C4—C3—H3A | 108.8 | N1—C7—H7 | 126.8 |
C2—C3—H3B | 108.8 | C7—C8—N2 | 106.6 (2) |
C4—C3—H3B | 108.8 | C7—C8—H8A | 126.7 |
H3A—C3—H3B | 107.7 | N2—C8—H8A | 126.7 |
C5—C4—C3 | 116.7 (8) | C6—C9—H9A | 109.5 |
C5—C4—H4A | 108.1 | C6—C9—H9B | 109.5 |
C3—C4—H4A | 108.1 | H9A—C9—H9B | 109.5 |
C5—C4—H4B | 108.1 | C6—C9—H9C | 109.5 |
C3—C4—H4B | 108.1 | H9A—C9—H9C | 109.5 |
H4A—C4—H4B | 107.3 | H9B—C9—H9C | 109.5 |
C4—C5—H5A | 109.5 | ||
Sn1i—O2—C1—O1 | 177.81 (15) | C7—N1—C6—N2 | 0.7 (3) |
Sn1i—O2—C1—C1i | −1.5 (3) | C7—N1—C6—C9 | −178.6 (3) |
Sn1—O1—C1—O2 | 178.19 (15) | C8—N2—C6—N1 | −0.6 (3) |
Sn1—O1—C1—C1i | −2.5 (3) | C8—N2—C6—C9 | 178.7 (3) |
Sn1—C2—C3—C4 | 179.1 (5) | C6—N1—C7—C8 | −0.5 (3) |
C2—C3—C4—C5 | −174.8 (6) | N1—C7—C8—N2 | 0.1 (3) |
Sn1—C2—C3A—C4A | −170.7 (8) | C6—N2—C8—C7 | 0.3 (3) |
C2—C3A—C4A—C5A | −83.0 (15) |
Symmetry code: (i) −x+1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···Cl1 | 0.74 (3) | 2.75 (3) | 3.398 (2) | 147 (3) |
N1—H1N···O1 | 0.74 (3) | 2.44 (3) | 2.993 (2) | 133 (3) |
N2—H2N···Cl2ii | 0.77 (2) | 2.43 (3) | 3.187 (2) | 170 (2) |
C7—H7···Cl3iii | 0.95 | 2.87 | 3.517 (2) | 127 |
C9—H9A···Cl1 | 0.98 | 2.92 | 3.696 (3) | 136 |
Symmetry codes: (ii) x, y, z−1; (iii) −x+1, y−1/2, −z+1/2. |
Acknowledgements
The authors acknowledge the Cheikh Anta Diop University of Dakar (Sénégal) and the University of Notre Dame (USA) for financial support.
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