Tetramethylammonium aquatrichloridooxalatostannate(IV) monohydrate

The SnIV atom in the title compound, [(CH3)4N][Sn(C2O4)Cl3(H2O)]·H2O, obtained from the reaction between SnCl4 and [(CH3)4N]2C2O4·2H2O, is six-coordinated by three Cl atoms, an O atom of a water molecule and two O atoms from an asymmetrically chelating oxalate anion. The environment around the SnIV atom is distorted octahedral. The anions are connected by the lattice water molecule through O—H⋯O hydrogen bonds, leading to a layered structure parallel to (010). The cations are located between these layers and besides Coulombic forces are connected to the anionic layers through weak C—H⋯O and C—H⋯Cl interactions.

The Sn IV atom in the title compound, [(CH 3 ) 4 N] [Sn(C 2 O 4 )Cl 3 -(H 2 O)]ÁH 2 O, obtained from the reaction between SnCl 4 and [(CH 3 ) 4 N] 2 C 2 O 4 Á2H 2 O, is six-coordinated by three Cl atoms, an O atom of a water molecule and two O atoms from an asymmetrically chelating oxalate anion. The environment around the Sn IV atom is distorted octahedral. The anions are connected by the lattice water molecule through O-HÁ Á ÁO hydrogen bonds, leading to a layered structure parallel to (010). The cations are located between these layers and besides Coulombic forces are connected to the anionic layers through weak C-HÁ Á ÁO and C-HÁ Á ÁCl interactions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2712).  Tudela et al. (1986). Our group has previously reported the crystal structure of ((n-C 3 H 7 ) 2 NH 2 ) 2 [Sn(C 2 O 4 )Cl 4 ] which contains a chelating oxalate anion, and the environment of tin(IV) being likewise octahedral (Sow et al., 2010). In the context of our search for new SnX 4 adducts we report here the study of the reaction between ((CH 3 ) 4 N) 2 C 2 O 4 . 2H 2 O and SnCl 4 which has yielded the title compound, ((CH 3 While many SnX 4 adducts have been reported (see above), a complex with a [SnCl 3 ]-containing residue is reported here.
The octahedral geometry around the tin(IV) atom is defined by three Cl atoms, two oxygen atoms from the chelating oxalate anion and the oxygen atom of a water molecule ( The water molecule bonded to the tin(IV) atom is also hydrogen-bonded to the O4 atom of a neighbour complex-anion.
The lattice water molecule O6 is bonded to O3 and O4 of the same oxalate anion through a bifurcated hydrogen bond and to a O3 atom of a neighbouring oxalate anion, leading to a layered structure extending parallel to (010). The cations are located between the anionic planes (Figs. 2,3). In the crystal packing, C-H···O and C-H···Cl interactions between cations and anions are also observed ( Table 1) (Fernandez et al., 2002;Hazell et al., 1998;Sow et al., 2010).
in the typical range of C-O and C═O bonds (Ng & Kumar Das, 1993;Xu et al., 2003).

Experimental
All chemicals were purchased from Aldrich (Germany) and used without any further purification. ((CH 3 ) 4 N) 2 C 2 O 4 . 2H 2 O has been obtained on allowing ((CH 3 ) 4 N)OH as a 20% water solution to react with oxalic acid in a 2:1 ratio. A powder is obtained after evaporation of water at 333 K. On allowing the oxalic acid salt to react with SnCl 4 in a 1:1 ratio in ethanol, a colorless solution is obtained, which gives, after slow solvent evaporation, crystals suitable for X-ray determination .

Refinement
Water molecule hydrogen atoms have been located in the difference fourier map and were refined with an idealized bond lenght of 0.85 Å. The other hydrogen atoms have been placed onto calculated position and were refined using a riding model, with C-H distances of 0.98 Å and U iso (H) = 1.5U eq (C).

Figure 1
The asymmetric unit showing the numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Special details
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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.