Dichloridodi-μ2-hydroxido-di-μ3-oxido-octaphenyltetratin(IV) dimethyl sulfoxide disolvate

In the centrosymmetric tetranuclear title molecule, [Sn4(C6H5)8Cl2O2(OH)2]·2C2H6OS, the two independent tinIV atoms show distorted trigonal–bipyramidal SnC2O3 and SnC2O2Cl coordination geometries. The four tinIV atoms are bridged by the hydroxo and oxo ligands, forming a ladder-like array of three edge-connected Sn2O2 squares. The solvent molecules are linked to the tetranuclear molecule via O–H⋯O hydrogen bonds.

In the centrosymmetric tetranuclear title molecule, [Sn 4 (C 6 H 5 ) 8 Cl 2 O 2 (OH) 2 ]Á2C 2 H 6 OS, the two independent tin IV atoms show distorted trigonal-bipyramidal SnC 2 O 3 and SnC 2 O 2 Cl coordination geometries. The four tin IV atoms are bridged by the hydroxo and oxo ligands, forming a ladder-like array of three edge-connected Sn 2 O 2 squares. The solvent molecules are linked to the tetranuclear molecule via O-HÁ Á ÁO hydrogen bonds.

Comment
Organotin(IV) complexes have been studied due to the diversity of structures that such compounds can form and in view of their potential biological activities (Davies & Smith, 1982). Herewith we present the title compound (I).
In (I) (Fig. 1), all geometric parameters are normal and correspond to those reported for related compounds (Vollano et al., 1984;Kresinski et al., 1994) The similar structure with bromide (instead of chloride) anions was reported by Yap et al. (2010). All tin atoms are five-coordinated, form distorted trigonal-bipyramidal environments. Oxide or hydroxide groups play bridging role between Sn atoms. Each of the inner Sn IV atoms is coordinated by three O atoms in the equatorial plane and two phenyl rings in axial position. The equatorial angle is shorter than ideally 180° being only 124.24 (11) °. The Sn2-O1 and Sn2-O2 bond distances are 2.0451 (18) and 2.1630 (19) Å, respectively. Each of the outer Sn IV atoms is coordinated by one chloride and two O atoms in equatorial plane and axial positions are occupied by two phenyl rings. The Sn1-Cl1 bond distance is 2.4628 (9) Å and axial angle, C1-Sn2-C7 is 120.35 (11) °. The centrosymmetric tetrameric species bears a central part which consists of Sn 2 O 2 ring with two adjacent Sn 2 O(OH) fourmembered rings. This behavior is also consistent with the reported structure. The DMSO molecules accompany the tetranuclear compound by O2-H2A···O3 hydrogen bonds.

Experimental
The solution of 2-mercaptobenzaldehyde (2.76 g, 20 mmol) in 15 ml e thanol was added to solution of diethylamine (0.6 g, 10 mmol) in 10 ml e thanol. The obtained mixture was refluxed at 60 C for 4 h. The yellow crystals of the product was filtered off and dried. In order to synthesis of the title compound, the obtained ligand and dichloridediphenyltin were dissolved in DMSO at ambient temperature. Colourless crystals of the tetramer suitable for X-ray were obtained by slow evaporation of the solvent within one month.

Refinement
O-bound H atom was found in a difference Fourier map and isotropically refined with O-H distance restraint of 0.824 (19) Å. C-bound H atoms were positioned geometrically and refined as riding atoms with C-H = 0.93-0.96 Å, and U iso (H) = 1.2-1.5 U eq (C).
Solvent molecule and C-bound H atoms were omitted for clarity.

Crystal data
[Sn 4 (C 6 H 5 ) 8 Cl 2 O 2 (OH) 2 ]·2C 2 H 6 OS M r = 1384.73 Monoclinic, P2 1 /n Hall symbol: -P 2yn a = 11.521 (2) 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.