Structural Variation in Diorganotin Dimethylxanthates, R2Sn(S2COMe)2:  A Combined Crystallographic and Theoretical Investigation

• Published in: Organometallics 2000-12, Vol.19 (25), p.5410-5415
• Main Authors: Mohamed-Ibrahim, Mohamed Ismail, Chee, Suan See, Buntine, Mark A, Cox, Michael J, Tiekink, Edward R. T
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om000717v

The crystal and molecular structures of three R2Sn(S2COMe)2 compounds have been determined and show that the tin atom in each case exists in a distorted trapezoidal bipyramidal geometry with the tin-bound organo substituents lying over the longer edge of the trapezoidal plane. For Me2Sn(S2COMe)2, one of the xanthate ligands coordinates via both sulfur atoms (S-,S- chelation) but the other uses one sulfur and the oxygen atom in coordination to tin (S-,O- chelation). More conventional geometries, with S-,S- chelation only, are found for Ph(Me)Sn(S2COMe)2 and Ph2Sn(S2COMe)2. Theoretical predictions of the isolated molecular structures have been calculated using ab initio and density functional theories (all with the 3-21G** basis set) and reveal a different arrangement of the ligand donor set for each compound, i.e., one featuring both ligands with S-,O- chelation. Differences between the single-molecule and solid-state structures are ascribed to the influence of intermolecular interactions on the molecular geometries in the solid state.