Di-μ-chlorido-bis[chloridobis(dimethyl sulfoxide-κO)tin(II)]

The structure of the title compound, [Sn2Cl4(C2H6OS)4], contains dimers formed through weak Sn⋯Cl [3.691 (2) Å] interactions, resulting in a planar Sn2Cl2 core with an inversion center at the centre of the four-membered ring. The SnII atoms are pentacoordinated and have a distorted octahedral Ψ-SnCl3O2 coordination geometry. The O atoms from the dimethyl sulfoxide molecules occupy trans positions, while the Cl atoms exhibit a meridional arrangement.


Comment
In an attempt to perform an oxidative addition of SnCl 2 to an organic halide, the title compound was isolated as a by-product. In the dimer unit the tin atom is pentacoordinated in a distorted pseudo-octahedral coordination geometry, with the two chlorine atoms from the same molecular unit in cis positions [Cl1-Sn1-Cl2 = 93.86 (7)°] and a bridging chlorine atom trans to the free position. In contrast, in SnCl 4 .2DMSO (Kisenyi et al., 1985) the tin atom is hexacoordinated, with the oxygen atoms from the dimethylsulfoxide in cis position, while the structure of SnCl 2 .2H 2 O is described as pyramidal (Kiriyama et al., 1973) with only one water molecule bonded to the metal center.
In the strucure the dimers are stacked along the a axis and form layers stacking along the b axis, with alternate arrangement of the dimeric units in consecutive layers (Figure 3).

Experimental
The title compound was isolated as a by-product after the workup of the reaction between SnCl 2 to an organic halide performed in hot dimethyl sulfoxide (DMSO).
supplementary materials sup-2 Refinement All hydrogen atoms were placed in calculated positions using a riding model, with C-H = 0.96 Å and with U iso = 1.5U eq (C) for methyl H.
The data collection was done with 2 second irradiation time per frame over the complete sphere for a total data collection time of 2 hours. An earlier attempt to measure a crystal with a 10 second irradiation time per frame resulted in crystal decay after approximately 3 hours.

Special details
Geometry. All e.s. 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 Rfactors(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.