Mössbauer and single crystal X-ray studies of polymeric dimethylchlorotin acetate

The solid state structure of dimethylchlorotin acetate has been investigated by Mössbauer spectroscopy and single crystal X-ray analysis. Tin-119 Mössbauer spectra have been recorded at 80 K and 300 K, and the measured isomer shift and quadrupole splitting parameters have been correlated with the crystallographic data. The crystal structure has been determined using heavy-atom methods in conjunction with least-squares refinement of data measured on a two-circle X-ray diffractometer. Crystals are orthorhombic, space group Pna2₁, with four formula weights in a cell having the dimensions a = 9.315(3), b = 11.061(3), c = 7.656(2) Å and U = 788.78 ų. The observed and calculated densities are 2.07 and 2.05 mg m^?3, respectively. The structure was refined using 842 observed reflections to give conventional discrepancy factors of R = 0.040 and R' = 0.044. The crystal structure is composed of Me₂ClSn units bridged by acetate ligands giving rise to polymeric chains which run along the a direction. The tin atom is in a distorted trigonal bipyramidal environment consisting of two axial oxygen atoms distanced 2.165(6) and 2,392(7) Å from the metal, and equatorial positions occupied by two methyl groups and a chlorine atom. Distortions within the coordination polyhedron may be attributed to a further weak but apparently significant tin-oxygen interaction (Sn-O 2.782(7) Å), resulting in the tin atom becoming six-coordinate.