inorganic compounds
Hydrates of tin tetrachloride
aSchool of Chemistry, University of Southampton, Southampton SO17 1BJ, England
*Correspondence e-mail: m.webster@soton.ac.uk
The crystal structures of the tri- and tetrahydrate of tin tetrachloride, viz. diaquatetrachlorotin(IV) monohydrate, [SnCl4(H2O)2]·H2O, and diaquatetrachlorotin(IV) dihydrate, [SnCl4(H2O)2]·2H2O, are reported and shown to contain the cis-[SnCl4(H2O)2] species and water molecules in both cases. The trihydrate contains chains of the tin species linked by a single hydrogen-bonded water molecule, whilst the tetrahydrate has a three-dimensional network. In addition, there are O—H⋯Cl interactions present.
Comment
The literature reports several hydrates of tin tetrachloride, including the tri-, tetra- and pentahydrate, but only the last is commercially available [see Klug & Brasted (1958) and Gmelins Handbuch der Anorganischen Chemie (1972)] and it has been structurally characterized using a crystal selected from a commercial bulk sample (Barnes et al., 1980). As part of a systematic study of interactions between main group elements and acyclic and macrocyclic chalcogenoether ligands, we have isolated and structurally characterized several new families of donor–acceptor compounds involving SnIV halides with thio-, seleno- and telluroether ligands (Levason & Reid, 2001; Levason et al., 2003). In the course of this work, we have also obtained crystals which have been shown to be hydrates of SnCl4. These experiments were carried out under `anhydrous' conditions and clearly the products arose from small amounts of water in the solvents/reagents or ingress of water from the air during manipulations.
By this route, we have prepared and determined the crystal structures of the tri- and tetrahydrate of tin tetrachloride and this has provided an opportunity to compare the two title structures with that of the pentahydrate and to establish if there are features common to all three hydrates, both in the tin species present and in the nature of the hydrogen bonding. The structure analysis of the pentahydrate (Barnes et al., 1980) did not locate the H atoms, but the O⋯O and O⋯Cl distances gave convincing indications of O—H⋯O and O—H⋯Cl interactions.
The trihydrate, SnCl4·3H2O or [SnCl4(H2O)2]·H2O, has been isolated on two occasions and contains a cis-octahedral [SnCl4(H2O)2] group linked into chains by solvate water molecules through O—H⋯O hydrogen bonds (Fig. 1). The only initial problem arose from the closeness of the cell β parameter to 90° and one of the crystals was shown to be a twin. The data reported are for the non-twin crystal, but the results for the two determinations are essentially identical and gave rise to similar R values. All the H atoms were identified: the tin-bonded water molecules are hydrogen bonded to O3 and by a second hydrogen bond to a Cl atom (Table 1). The hydrate water, in contrast, is hydrogen bonded to Cl, with each H atom involved in a bifurcated hydrogen bond with rather small O—H⋯Cl angles (121–146°). The Sn—Cl [2.338 (1)–2.401 (1) Å] and Sn—O [2.138 (3) and 2.169 (3) Å] distances are unexceptional.
The tetrahydrate, SnCl4·4H2O or [SnCl4(H2O)2]·2H2O, like the trihydrate, contains cis-octahedral [SnCl4(H2O)2] groups, but with a more complicated three-dimensional network of O—H⋯O bonds (Fig. 2). Only the H atoms of the bonded water molecules were clearly identified and included in the model, although there was evidence for some H atoms of the hydrate waters, but this was not convincing. All eight H atoms of the coordinated water molecules are involved in hydrogen bonding, with H1 and H8 forming O—H⋯Cl linkages, the remainder forming O—H⋯O linkages (Table 2). Judged solely by distance (no H atoms being available), O5⋯O6 [2.745 (8) Å] and O7⋯O8a [2.966 (9) Å; symmetry code: (a) x, 1 − y, ½ + z] form O—H⋯O hydrogen bonds. Short chains of hydrogen-bonded O atoms linking [SnCl4(H2O)2] groups are easily recognized [e.g. O1⋯O5⋯O6⋯O4b; symmetry code: (b) ½ + x, − y, ½ + z]. The Sn—Cl [2.359 (2)–2.397 (2) Å] and Sn—O [2.106 (5)–2.137 (6) Å] distances are again unexceptional.
The structure of the pentahydrate, SnCl4·5H2O (Barnes et al., 1980), again shows the cis-[SnCl4(H2O)2] moiety linked into chains parallel to c through three hydrate water molecules. There is further O—H⋯O linking to a parallel chain (Fig. 3) and, judged by O⋯Cl distances, there is additional weak hydrogen bonding between the double chains. Finally, the [SnCl4(H2O)2] unit has been found in a number (ca six) of complexes of and similar molecules [see Cusack et al. (1984) and Junk & Raston (2004)]. Four examples are hydrates and involve hydrogen bonding between the tin residue and the hydrate water and organic O atoms. Surprisingly, one example (Hough et al., 1986) contains the trans-[SnCl4(H2O)2] group, with the rest containing the by now familiar cis geometric isomer.
Experimental
Crystals were obtained serendipitously during attempts to crystallize SnCl4 complexes of dithioether and tetrathia-macrocycles from CH2Cl2. Removal of the bulk thioether complex by filtration and slow evaporation of the residual filtrate unexpectedly yielded crystals of the tri- and tetrahydrate of SnCl4.
Trihydrate SnCl4·3H2O
Crystal data
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Data collection
Refinement
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Tetrahydrate SnCl4·4H2O
Crystal data
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Data collection
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For the trihydrate, all the H atoms were located from a difference electron-density map and refined using restraints on the O—H bond distances (0.84 Å). H atoms were given a common refined displacement parameter. For the tetrahydrate, a difference electron-density map showed a number of peaks for potential H atoms, of which the eight of the tin-bonded water molecules were the most convincing, with reasonable O—H, H—O—H and H—O—Sn geometry. Inclusion of these with restraints (DFIX) gave a satisfactory model. The H atoms on the hydrate water molecules were incomplete, with poor H—O—H angles (in two cases where both H atoms were located), and ) parameter for the tetrahydrate was determined from a small number of reflections, which makes the determination of the chosen crystals less reliable. The H atoms were fixed in the final cycle as the shift/error values were small but failing to converge probably due to the large correlation coefficients between the H-atom coordinates.
calculations gave unsatisfactory intermolecular H⋯H distances. Accordingly, these H atoms were excluded from the model. The Flack (1983For both compounds, data collection and cell MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); data reduction: TEXSAN (Molecular Structure Corporation, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S0108270104005633/gd1307sup1.cif
contains datablocks I, II, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S0108270104005633/gd1307Isup2.hkl
Structure factors: contains datablock II. DOI: 10.1107/S0108270104005633/gd1307IIsup3.hkl
Crystals were obtained serendipitously during attempts to crystallize SnCl4 complexes of dithioether and tetrathia-macrocycles from CH2Cl2. Removal of the bulk thioether complex by filtration and slow evaporation of the residual filtrate unexpectedly yielded crystals of the tri- and tetrahydrates of SnCl4.
For the trihydrate, all the H atoms were located from a difference electron-density map and refined using restraints on the O—H bond distances (0.84 Å). H atoms were given a common refined displacement parameter. For the tetrahydrate, a difference electron-density map showed a number of peaks for potential H atoms, of which the eight of the tin-bonded water molecules were the most convincing, with reasonable O—H, H—O—H and H—O—Sn geometry. Inclusion of these with restraints (DFIX) gave a satisfactory model. The H atoms on the hydrate water molecules were incomplete, with poor H—O—H angles (in two cases where both H atoms were located) and
calculations gave unsatisfactory intermolecular H···H distances. Accordingly, these H atoms were excluded from the model. The Flack (1983) parameter for the tetrahydrate was determined from a small number of reflections which makes the determination of the chosen crystals less reliable. The H atoms were fixed in the final cycle as the shift/error values were small but failing to converge probably due to the large correlation coefficients between the H-atom coordinates.For both compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).
Fig. 1. Packing diagram for [SnCl4(H2O)2]·H2O, viewed along the a direction. O—H···O hydrogen bonds are shown as dotted lines and displacement ellipsoids are drawn at the 50% probability level. | |
Fig. 2. Packing diagram for [SnCl4(H2O)2]·2H2O, viewed along the b direction. H atoms are only included in the model for atoms O1 to O4, but are excluded from the diagram for clarity. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry code: (a) x, 1 − y, 1/2 + z.] | |
Fig. 3. Schematic diagram of the O—H···O hydrogen bonding in [SnCl4(H2O)2]·3H2O, showing the double chains. The only O atoms shown are O1, part of [SnCl4(H2O)2], and the hydrate atoms O2 and O3. |
[SnCl4(H2O)2]·H2O | F(000) = 592 |
Mr = 314.54 | Dx = 2.494 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 25 reflections |
a = 6.362 (3) Å | θ = 23.0–24.9° |
b = 11.071 (4) Å | µ = 4.26 mm−1 |
c = 11.895 (4) Å | T = 150 K |
β = 90.22 (2)° | Block, colourless |
V = 837.8 (6) Å3 | 0.48 × 0.28 × 0.20 mm |
Z = 4 |
Rigaku AFC-7S diffractometer | 1356 reflections with I > 2σ(I) |
Radiation source: fine-focus Mo sealed tube | Rint = 0.011 |
Graphite monochromator | θmax = 25.0°, θmin = 2.5° |
ω/2θ scans | h = −7→7 |
Absorption correction: ψ scan (North et al., 1968) | k = 0→13 |
Tmin = 0.268, Tmax = 0.427 | l = 0→14 |
1549 measured reflections | 3 standard reflections every 200 reflections |
1475 independent reflections | intensity decay: none |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0569P)2 + 1.1933P] where P = (Fo2 + 2Fc2)/3 |
1475 reflections | (Δ/σ)max = 0.001 |
92 parameters | Δρmax = 0.83 e Å−3 |
7 restraints | Δρmin = −2.44 e Å−3 |
[SnCl4(H2O)2]·H2O | V = 837.8 (6) Å3 |
Mr = 314.54 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 6.362 (3) Å | µ = 4.26 mm−1 |
b = 11.071 (4) Å | T = 150 K |
c = 11.895 (4) Å | 0.48 × 0.28 × 0.20 mm |
β = 90.22 (2)° |
Rigaku AFC-7S diffractometer | 1356 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.011 |
Tmin = 0.268, Tmax = 0.427 | 3 standard reflections every 200 reflections |
1549 measured reflections | intensity decay: none |
1475 independent reflections |
R[F2 > 2σ(F2)] = 0.029 | 7 restraints |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.83 e Å−3 |
1475 reflections | Δρmin = −2.44 e Å−3 |
92 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. DFIX used on the d(O—H) distances with a target distance 0.84 (2) Angstrom. H atoms given a common refined adp. |
x | y | z | Uiso*/Ueq | ||
Sn1 | 0.36858 (4) | 0.23528 (3) | 0.66346 (2) | 0.01350 (15) | |
Cl1 | 0.23914 (17) | 0.09273 (10) | 0.53026 (9) | 0.0210 (3) | |
Cl2 | 0.69212 (16) | 0.13053 (9) | 0.68652 (9) | 0.0179 (2) | |
Cl3 | 0.21634 (17) | 0.13467 (10) | 0.82238 (9) | 0.0199 (3) | |
Cl4 | 0.09960 (18) | 0.37715 (10) | 0.64014 (10) | 0.0238 (3) | |
O1 | 0.5134 (5) | 0.3672 (3) | 0.7697 (3) | 0.0198 (7) | |
O2 | 0.5277 (5) | 0.3335 (3) | 0.5309 (3) | 0.0209 (7) | |
O3 | 0.8115 (5) | 0.2091 (3) | 0.4126 (3) | 0.0238 (7) | |
H1 | 0.582 (9) | 0.353 (7) | 0.827 (3) | 0.057 (9)* | |
H2 | 0.446 (10) | 0.425 (4) | 0.797 (5) | 0.057 (9)* | |
H3 | 0.450 (10) | 0.350 (7) | 0.475 (4) | 0.057 (9)* | |
H4 | 0.603 (10) | 0.289 (6) | 0.492 (5) | 0.057 (9)* | |
H5 | 0.884 (9) | 0.242 (6) | 0.362 (4) | 0.057 (9)* | |
H6 | 0.876 (10) | 0.161 (5) | 0.454 (5) | 0.057 (9)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sn1 | 0.0129 (2) | 0.0107 (2) | 0.0169 (2) | 0.00045 (10) | −0.00213 (13) | −0.00132 (10) |
Cl1 | 0.0221 (6) | 0.0173 (5) | 0.0235 (6) | 0.0010 (4) | −0.0064 (4) | −0.0064 (4) |
Cl2 | 0.0145 (5) | 0.0143 (5) | 0.0248 (5) | 0.0022 (4) | −0.0031 (4) | −0.0007 (4) |
Cl3 | 0.0184 (5) | 0.0205 (6) | 0.0209 (5) | −0.0029 (4) | 0.0003 (4) | 0.0002 (4) |
Cl4 | 0.0191 (6) | 0.0182 (5) | 0.0339 (6) | 0.0073 (4) | −0.0045 (4) | −0.0025 (5) |
O1 | 0.0218 (17) | 0.0121 (15) | 0.0254 (17) | 0.0012 (12) | −0.0075 (13) | −0.0062 (13) |
O2 | 0.0195 (17) | 0.0211 (17) | 0.0222 (17) | −0.0014 (13) | −0.0008 (13) | 0.0035 (13) |
O3 | 0.0185 (17) | 0.0308 (18) | 0.0221 (17) | 0.0008 (15) | −0.0024 (13) | 0.0070 (15) |
Sn1—Cl1 | 2.3810 (12) | O1—H1 | 0.82 (2) |
Sn1—Cl2 | 2.3775 (13) | O1—H2 | 0.84 (5) |
Sn1—Cl3 | 2.4013 (13) | O2—H3 | 0.85 (5) |
Sn1—Cl4 | 2.3384 (12) | O2—H4 | 0.83 (6) |
Sn1—O1 | 2.138 (3) | O3—H5 | 0.84 (6) |
Sn1—O2 | 2.169 (3) | O3—H6 | 0.83 (6) |
O1—Sn1—O2 | 83.46 (13) | Cl2—Sn1—Cl1 | 92.90 (4) |
O1—Sn1—Cl4 | 85.69 (9) | Cl4—Sn1—Cl3 | 96.19 (5) |
O2—Sn1—Cl4 | 85.43 (10) | Cl2—Sn1—Cl3 | 91.98 (4) |
O1—Sn1—Cl3 | 91.47 (10) | Cl1—Sn1—Cl3 | 94.41 (5) |
O2—Sn1—Cl3 | 174.56 (9) | Sn1—O1—H1 | 126 (6) |
O1—Sn1—Cl2 | 83.92 (9) | Sn1—O1—H2 | 122 (5) |
O2—Sn1—Cl2 | 85.55 (9) | H1—O1—H2 | 96 (6) |
O1—Sn1—Cl1 | 173.42 (10) | Sn1—O2—H3 | 114 (5) |
O2—Sn1—Cl1 | 90.56 (9) | Sn1—O2—H4 | 112 (5) |
Cl4—Sn1—Cl2 | 166.94 (4) | H3—O2—H4 | 91 (7) |
Cl4—Sn1—Cl1 | 96.61 (5) | H5—O3—H6 | 115 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O3i | 0.82 (2) | 1.91 (3) | 2.678 (5) | 156 (6) |
O1—H2···Cl2ii | 0.84 (5) | 2.44 (3) | 3.238 (3) | 158 (6) |
O2—H3···Cl3iii | 0.85 (5) | 2.35 (6) | 3.188 (4) | 172 (7) |
O2—H4···O3 | 0.83 (6) | 1.85 (3) | 2.675 (5) | 169 (8) |
O3—H5···Cl3iv | 0.84 (6) | 2.56 (4) | 3.286 (4) | 144 (5) |
O3—H5···Cl2iii | 0.84 (6) | 2.80 (6) | 3.309 (4) | 121 (5) |
O3—H6···Cl1v | 0.83 (6) | 2.59 (5) | 3.315 (4) | 146 (7) |
O3—H6···Cl1vi | 0.83 (6) | 2.91 (6) | 3.425 (4) | 122 (6) |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, y+1/2, −z+3/2; (iii) x, −y+1/2, z−1/2; (iv) x+1, −y+1/2, z−1/2; (v) x+1, y, z; (vi) −x+1, −y, −z+1. |
[SnCl4(H2O)2]·2H2O | F(000) = 1264 |
Mr = 332.55 | Dx = 2.374 Mg m−3 |
Monoclinic, Cc | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: C -2yc | Cell parameters from 25 reflections |
a = 23.987 (4) Å | θ = 23.6–24.9° |
b = 6.714 (6) Å | µ = 3.85 mm−1 |
c = 11.580 (3) Å | T = 150 K |
β = 93.77 (2)° | Block, colourless |
V = 1860.9 (18) Å3 | 0.42 × 0.34 × 0.28 mm |
Z = 8 |
Rigaku AFC7S diffractometer | 1704 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.000 |
Graphite monochromator | θmax = 25.0°, θmin = 3.2° |
ω/2θ scans | h = −28→28 |
Absorption correction: ψ scan (North et al., 1968) | k = −7→0 |
Tmin = 0.241, Tmax = 0.340 | l = 0→13 |
1717 measured reflections | 3 standard reflections every 200 reflections |
1717 independent reflections | intensity decay: none |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | H-atom parameters not refined |
wR(F2) = 0.074 | w = 1/[σ2(Fo2) + (0.0598P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.13 | (Δ/σ)max < 0.001 |
1717 reflections | Δρmax = 0.94 e Å−3 |
164 parameters | Δρmin = −2.23 e Å−3 |
13 restraints | Absolute structure: Flack (1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.11 (3) |
[SnCl4(H2O)2]·2H2O | V = 1860.9 (18) Å3 |
Mr = 332.55 | Z = 8 |
Monoclinic, Cc | Mo Kα radiation |
a = 23.987 (4) Å | µ = 3.85 mm−1 |
b = 6.714 (6) Å | T = 150 K |
c = 11.580 (3) Å | 0.42 × 0.34 × 0.28 mm |
β = 93.77 (2)° |
Rigaku AFC7S diffractometer | 1704 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.000 |
Tmin = 0.241, Tmax = 0.340 | 3 standard reflections every 200 reflections |
1717 measured reflections | intensity decay: none |
1717 independent reflections |
R[F2 > 2σ(F2)] = 0.029 | H-atom parameters not refined |
wR(F2) = 0.074 | Δρmax = 0.94 e Å−3 |
S = 1.13 | Δρmin = −2.23 e Å−3 |
1717 reflections | Absolute structure: Flack (1983) |
164 parameters | Absolute structure parameter: 0.11 (3) |
13 restraints |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. The H atoms of the Sn bonded waters were included in the model. The other H atoms were less convincing as not all were found, did not refine well and these were excluded from the model. Restraints on O—H were used. Fixed H atoms in final cycle as shift/error were small but failing to converge probably due to large correlation between H atom parameters. Probably not enough Friedel related reflections (90) for a reliable absolute structure determination. |
x | y | z | Uiso*/Ueq | ||
Sn1 | 0.242986 (18) | 0.12803 (7) | 0.17477 (3) | 0.01388 (15) | |
Sn2 | −0.009876 (17) | 0.33648 (7) | −0.08266 (3) | 0.01389 (15) | |
Cl1 | 0.27173 (8) | −0.1780 (3) | 0.09203 (15) | 0.0199 (4) | |
Cl2 | 0.20962 (8) | 0.3850 (3) | 0.29478 (16) | 0.0215 (4) | |
Cl3 | 0.32761 (7) | 0.2997 (3) | 0.13795 (16) | 0.0224 (4) | |
Cl4 | 0.19213 (7) | 0.2397 (3) | 0.00579 (15) | 0.0228 (4) | |
Cl5 | −0.09836 (7) | 0.2192 (3) | −0.03083 (15) | 0.0234 (4) | |
Cl6 | 0.07409 (7) | 0.4236 (3) | −0.17073 (17) | 0.0223 (4) | |
Cl7 | 0.03933 (8) | 0.1873 (3) | 0.07930 (16) | 0.0257 (4) | |
Cl8 | −0.01963 (9) | 0.6577 (3) | 0.00414 (17) | 0.0235 (4) | |
O1 | 0.2850 (2) | 0.0240 (8) | 0.3316 (4) | 0.0189 (11) | |
O2 | 0.1741 (2) | −0.0426 (8) | 0.2246 (4) | 0.0205 (11) | |
O3 | −0.0049 (2) | 0.0798 (7) | −0.1859 (4) | 0.0182 (11) | |
O4 | −0.0534 (2) | 0.4506 (8) | −0.2354 (5) | 0.0240 (12) | |
O5 | 0.3170 (2) | 0.6573 (8) | 0.3650 (5) | 0.0224 (12) | |
O6 | 0.4130 (3) | 0.6733 (8) | 0.2488 (5) | 0.0230 (12) | |
O7 | 0.1290 (2) | 0.3042 (9) | 0.5742 (5) | 0.0296 (13) | |
O8 | 0.0935 (2) | 0.8945 (9) | −0.1473 (5) | 0.0267 (13) | |
H1 | 0.2773 | 0.0388 | 0.4005 | 0.037* | |
H2 | 0.2892 | −0.1003 | 0.3392 | 0.037* | |
H3 | 0.1456 | 0.0174 | 0.2477 | 0.037* | |
H4 | 0.1609 | −0.1099 | 0.1678 | 0.037* | |
H5 | 0.0229 | 0.0112 | −0.1618 | 0.037* | |
H6 | −0.0320 | 0.0012 | −0.1844 | 0.037* | |
H7 | −0.0637 | 0.5686 | −0.2296 | 0.037* | |
H8 | −0.0561 | 0.4042 | −0.3023 | 0.037* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sn1 | 0.0125 (2) | 0.0175 (2) | 0.0120 (2) | 0.00048 (19) | 0.00384 (17) | 0.0000 (2) |
Sn2 | 0.0124 (3) | 0.0178 (2) | 0.0119 (2) | −0.00094 (18) | 0.00420 (17) | 0.00003 (19) |
Cl1 | 0.0233 (10) | 0.0211 (8) | 0.0160 (8) | 0.0045 (7) | 0.0059 (7) | −0.0018 (7) |
Cl2 | 0.0200 (9) | 0.0208 (9) | 0.0246 (10) | 0.0015 (6) | 0.0068 (7) | −0.0053 (7) |
Cl3 | 0.0161 (8) | 0.0294 (10) | 0.0223 (9) | −0.0055 (7) | 0.0059 (7) | 0.0014 (8) |
Cl4 | 0.0209 (8) | 0.0307 (10) | 0.0166 (8) | 0.0034 (8) | 0.0004 (6) | 0.0047 (8) |
Cl5 | 0.0154 (8) | 0.0352 (11) | 0.0202 (9) | −0.0042 (8) | 0.0060 (6) | −0.0011 (8) |
Cl6 | 0.0167 (8) | 0.0283 (10) | 0.0228 (9) | −0.0047 (7) | 0.0082 (7) | 0.0002 (8) |
Cl7 | 0.0237 (9) | 0.0355 (11) | 0.0175 (9) | 0.0029 (8) | −0.0014 (7) | 0.0075 (8) |
Cl8 | 0.0330 (11) | 0.0183 (8) | 0.0199 (9) | −0.0003 (7) | 0.0063 (8) | −0.0027 (7) |
O1 | 0.027 (3) | 0.021 (3) | 0.009 (3) | 0.003 (2) | 0.0024 (19) | 0.000 (2) |
O2 | 0.023 (3) | 0.024 (3) | 0.016 (3) | −0.003 (2) | 0.008 (2) | −0.007 (2) |
O3 | 0.015 (3) | 0.015 (3) | 0.024 (3) | −0.002 (2) | 0.002 (2) | −0.007 (2) |
O4 | 0.025 (3) | 0.028 (3) | 0.018 (3) | 0.007 (2) | −0.002 (2) | −0.005 (2) |
O5 | 0.017 (3) | 0.029 (3) | 0.021 (3) | 0.006 (2) | 0.000 (2) | 0.001 (2) |
O6 | 0.029 (3) | 0.026 (3) | 0.014 (3) | −0.003 (2) | −0.001 (2) | −0.001 (2) |
O7 | 0.027 (3) | 0.031 (3) | 0.030 (3) | 0.006 (2) | 0.003 (2) | 0.006 (3) |
O8 | 0.018 (3) | 0.034 (3) | 0.029 (3) | 0.000 (2) | 0.011 (2) | 0.005 (3) |
Sn1—O2 | 2.121 (5) | Sn2—Cl6 | 2.3895 (18) |
Sn1—O1 | 2.136 (5) | Sn2—Cl8 | 2.397 (3) |
Sn1—Cl4 | 2.3591 (19) | O1—H1 | 0.8368 |
Sn1—Cl2 | 2.386 (2) | O1—H2 | 0.8448 |
Sn1—Cl1 | 2.388 (2) | O2—H3 | 0.8530 |
Sn1—Cl3 | 2.3968 (19) | O2—H4 | 0.8430 |
Sn2—O3 | 2.106 (5) | O3—H5 | 0.8420 |
Sn2—O4 | 2.137 (6) | O3—H6 | 0.8380 |
Sn2—Cl7 | 2.371 (2) | O4—H7 | 0.8336 |
Sn2—Cl5 | 2.3775 (19) | O4—H8 | 0.8338 |
O2—Sn1—O1 | 85.7 (2) | O3—Sn2—Cl6 | 82.94 (15) |
O2—Sn1—Cl4 | 91.59 (15) | O4—Sn2—Cl6 | 86.49 (17) |
O1—Sn1—Cl4 | 177.05 (16) | Cl7—Sn2—Cl6 | 92.94 (7) |
O2—Sn1—Cl2 | 86.28 (15) | Cl5—Sn2—Cl6 | 168.64 (7) |
O1—Sn1—Cl2 | 84.19 (15) | O3—Sn2—Cl8 | 170.15 (15) |
Cl4—Sn1—Cl2 | 94.49 (8) | O4—Sn2—Cl8 | 88.20 (16) |
O2—Sn1—Cl1 | 83.97 (15) | Cl7—Sn2—Cl8 | 96.06 (8) |
O1—Sn1—Cl1 | 85.83 (15) | Cl5—Sn2—Cl8 | 94.51 (8) |
Cl4—Sn1—Cl1 | 95.04 (8) | Cl6—Sn2—Cl8 | 93.84 (8) |
Cl2—Sn1—Cl1 | 166.53 (7) | Sn1—O1—H1 | 130.5 |
O2—Sn1—Cl3 | 172.71 (15) | Sn1—O1—H2 | 117.2 |
O1—Sn1—Cl3 | 87.15 (15) | H1—O1—H2 | 92.9 |
Cl4—Sn1—Cl3 | 95.59 (7) | Sn1—O2—H3 | 119.1 |
Cl2—Sn1—Cl3 | 94.37 (8) | Sn1—O2—H4 | 109.8 |
Cl1—Sn1—Cl3 | 94.14 (8) | H3—O2—H4 | 103.2 |
O3—Sn2—O4 | 82.3 (2) | Sn2—O3—H5 | 109.4 |
O3—Sn2—Cl7 | 93.41 (16) | Sn2—O3—H6 | 115.5 |
O4—Sn2—Cl7 | 175.73 (16) | H5—O3—H6 | 104.3 |
O3—Sn2—Cl5 | 87.55 (14) | Sn2—O4—H7 | 113.9 |
O4—Sn2—Cl5 | 86.09 (17) | Sn2—O4—H8 | 129.7 |
Cl7—Sn2—Cl5 | 93.82 (7) | H7—O4—H8 | 115.2 |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···Cl1i | 0.84 | 2.42 | 3.223 (5) | 162 |
O1—H2···O5ii | 0.84 | 1.78 | 2.600 (8) | 164 |
O2—H3···O8iii | 0.85 | 1.89 | 2.703 (7) | 158 |
O2—H4···O7iv | 0.84 | 1.83 | 2.653 (8) | 165 |
O3—H5···O8ii | 0.84 | 1.86 | 2.680 (8) | 162 |
O3—H6···O6v | 0.84 | 1.89 | 2.672 (8) | 154 |
O4—H7···O6vi | 0.83 | 1.83 | 2.653 (8) | 167 |
O4—H8···Cl8vii | 0.83 | 2.49 | 3.256 (6) | 153 |
Symmetry codes: (i) x, −y, z+1/2; (ii) x, y−1, z; (iii) x, −y+1, z+1/2; (iv) x, −y, z−1/2; (v) x−1/2, −y+1/2, z−1/2; (vi) x−1/2, −y+3/2, z−1/2; (vii) x, −y+1, z−1/2. |
Experimental details
(I) | (II) | |
Crystal data | ||
Chemical formula | [SnCl4(H2O)2]·H2O | [SnCl4(H2O)2]·2H2O |
Mr | 314.54 | 332.55 |
Crystal system, space group | Monoclinic, P21/c | Monoclinic, Cc |
Temperature (K) | 150 | 150 |
a, b, c (Å) | 6.362 (3), 11.071 (4), 11.895 (4) | 23.987 (4), 6.714 (6), 11.580 (3) |
β (°) | 90.22 (2) | 93.77 (2) |
V (Å3) | 837.8 (6) | 1860.9 (18) |
Z | 4 | 8 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 4.26 | 3.85 |
Crystal size (mm) | 0.48 × 0.28 × 0.20 | 0.42 × 0.34 × 0.28 |
Data collection | ||
Diffractometer | Rigaku AFC-7S diffractometer | Rigaku AFC7S diffractometer |
Absorption correction | ψ scan (North et al., 1968) | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.268, 0.427 | 0.241, 0.340 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1549, 1475, 1356 | 1717, 1717, 1704 |
Rint | 0.011 | 0.000 |
(sin θ/λ)max (Å−1) | 0.595 | 0.595 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.082, 1.07 | 0.029, 0.074, 1.13 |
No. of reflections | 1475 | 1717 |
No. of parameters | 92 | 164 |
No. of restraints | 7 | 13 |
H-atom treatment | H-atom parameters constrained | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.83, −2.44 | 0.94, −2.23 |
Absolute structure | ? | Flack (1983) |
Absolute structure parameter | ? | 0.11 (3) |
Computer programs: SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O3i | 0.82 (2) | 1.91 (3) | 2.678 (5) | 156 (6) |
O1—H2···Cl2ii | 0.84 (5) | 2.44 (3) | 3.238 (3) | 158 (6) |
O2—H3···Cl3iii | 0.85 (5) | 2.35 (6) | 3.188 (4) | 172 (7) |
O2—H4···O3 | 0.83 (6) | 1.85 (3) | 2.675 (5) | 169 (8) |
O3—H5···Cl3iv | 0.84 (6) | 2.56 (4) | 3.286 (4) | 144 (5) |
O3—H5···Cl2iii | 0.84 (6) | 2.80 (6) | 3.309 (4) | 121 (5) |
O3—H6···Cl1v | 0.83 (6) | 2.59 (5) | 3.315 (4) | 146 (7) |
O3—H6···Cl1vi | 0.83 (6) | 2.91 (6) | 3.425 (4) | 122 (6) |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, y+1/2, −z+3/2; (iii) x, −y+1/2, z−1/2; (iv) x+1, −y+1/2, z−1/2; (v) x+1, y, z; (vi) −x+1, −y, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···Cl1i | 0.84 | 2.42 | 3.223 (5) | 162 |
O1—H2···O5ii | 0.84 | 1.78 | 2.600 (8) | 164 |
O2—H3···O8iii | 0.85 | 1.89 | 2.703 (7) | 158 |
O2—H4···O7iv | 0.84 | 1.83 | 2.653 (8) | 165 |
O3—H5···O8ii | 0.84 | 1.86 | 2.680 (8) | 162 |
O3—H6···O6v | 0.84 | 1.89 | 2.672 (8) | 154 |
O4—H7···O6vi | 0.83 | 1.83 | 2.653 (8) | 167 |
O4—H8···Cl8vii | 0.83 | 2.49 | 3.256 (6) | 153 |
Symmetry codes: (i) x, −y, z+1/2; (ii) x, y−1, z; (iii) x, −y+1, z+1/2; (iv) x, −y, z−1/2; (v) x−1/2, −y+1/2, z−1/2; (vi) x−1/2, −y+3/2, z−1/2; (vii) x, −y+1, z−1/2. |
Acknowledgements
The authors thank the EPSRC for access to the chemical database service at Daresbury.
References
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The literature reports several hydrates of tin tetrachloride, including the tri-, tetra- and pentahydrates, but only the latter is commercially available [see, for examples, Klug & Brasted (1958) and Gmelins Handbuch der Anorganischen Chemie (1972)]. Only the pentahydrate has been structurally characterized using a crystal selected from a commercial bulk sample (Barnes et al., 1980). As part of a systematic study of interactions between main group elements and acyclic and macrocyclic chalcogenoether ligands, we have isolated and structurally characterized several new families of donor–acceptor compounds involving SnIV halides with thio-, seleno- and telluroether ligands (Levason & Reid, 2001; Levason et al., 2003). In the course of this work, we have also obtained crystals which have been shown to be hydrates of SnCl4. These experiments were carried out under `anhydrous' conditions and clearly the products arose from small amounts of water in the solvents/reagents or ingress of water from the air during manipulations.
By this route, we have prepared and determined the crystal structures of the tri- and tetrahydrate and this has provided an opportunity to compare the three structures and to establish if there are features common to all, both in the tin species present and the nature of the hydrogen bonding. The structure analysis of the pentahydrate (Barnes et al., 1980) did not locate the H atoms but the O···O and O···Cl distances gave convincing indications of O—H···O and O—H···Cl interactions.
The trihydrate, SnCl4·3H2O or [SnCl4(H2O)2]·H2O, has been isolated on two occasions and contains a cis-octahedral SnCl4(H2O)2 group linked into chains by solvate water molecules through O—H···O hydrogen bonds (Fig. 1). The only initial problem arose from the closeness of the cell β parameter to 90° and one of the crystals was shown to be a twin. The data reported are from the non-twin crystal, but the results for the two determinations are essentially identical and give rise to similar R values. All the H atoms were identified: the tin-bonded water molecules are hydrogen bonded to O3 and by a second hydrogen bond to a Cl atom (Table 1). The hydrate water, in contrast, is hydrogen bonded to Cl, with each H atom involved in a bifurcated hydrogen bond with rather small O—H···Cl angles (121–146°). The Sn—Cl [2.338 (1)–2.401 (1) Å] and Sn—O [2.138 (3) and 2.169 (3) Å] distances are unexceptional.
The tetrahydrate, SnCl4·4H2O or [SnCl4(H2O)2]·2H2O, like the trihydrate, contains cis-octahedral SnCl4(H2O)2 groups, but with a more complicated three-dimensional network of O—H···O bonds (Fig. 2). Only the H atoms of the bonded water molecules were clearly identified and included in the model, although there was evidence for some H atoms of the hydrate waters but this was not convincing. All eight H atoms of the coordinated water molecules are involved in hydrogen bonding with H1 and H8, forming O—H···Cl linkages, the remainder being O—H···O (Table 2). Judged solely by distance (no H atoms being available), O5···O6 [2.745 (8) Å] and O7···O8a [2.966 (9) Å; symmetry code: (a) x, 1 − y, 1/2 + z] form O—H···O bonds. Short chains of hydrogen-bonded O atoms linking SnCl4(H2O)2 groups are easily recognized [e.g. O1—O5—O6—O4b; symmetry code: (b) 1/2 + x, 3/2 − y, 1/2 + z]. The Sn—Cl [2.359 (2)–2.397 (3) Å] and Sn—O [2.106 (5)–2.137 (6) Å] distances are unexceptional.
The structure of the pentahydrate, SnCl4·5H2O (Barnes et al., 1980), again shows the cis-[SnCl4(H2O)2] moiety linked into chains parallel to c through three hydrate water molecules. There is further O—H···O linking to a parallel chain (Fig. 3) and, judged by O···Cl distances, there is additional weak hydrogen bonding between the double chains. Finally, the SnCl4(H2O)2 unit has been found in a number (ca six) of complexes of crown ethers and similar molecules [see, for example, Cusack et al. (1984) and Junk & Raston (2004)]. Four examples are hydrates and involve hydrogen bonding between the tin residue and hydrate water and the organic O atoms. Surprisingly, one example (Hough et al., 1986) contains the trans-[SnCl4(H2O)2] group, with the rest containing the by now familiar cis geometric isomer.