Stereochemistry, and crystal and molecular structure, of meso- and rac-1,2-bis(phenylsulphinyl)ethane, cis-[meso-1,2-bis(phenylsulphinyl)ethane]dichloroplatinum(II), and cis-[rac-1,2-bis(phenylsulphinyl)ethane]dichloroplatinum(II)

Abstract

Diastereoisomeric meso and rac forms of 1,2-bis(phenylsulphinyl)ethane (1) and (2) respectively, have been separated and treated with K₂[PtCl₄] to obtain the title complexes (3) and (4) respectively. The crystal structures of (1) and of the enantiomeric (S,S) form of (2), indicated as (2a), as well as of (3) and (4), have been solved by X-ray analysis from three-dimensional counter data and refined by block-diagonal least squares to R 0.028 and 0.051 for the ligands, and by full-matrix least squares to R 0.030 and 0.056 for the complexes, respectively. The co-ordination around platinum, which involves two chlorides and two sulphur atoms of the organic ligand, is quite close to square planar for (4) and only slightly tetrahedrally distorted for (3). The lengths of the Pt–Cl bonds are in fairly good agreement with those found in square-planar platinum(II) complexes, whereas the Pt–S bonds are slightly shorter. The different conformations assumed by the ligand when unco-ordinated or co-ordinated to the metal are compared and discussed. The structural data are related to i.r. and ¹H n.m.r. measurements.