Stereochemical non-rigidity of dithioether complexes of trimethylplatinum(IV) halides. X-Ray crystal structures of [PtClMe3(MeSCH2CH2SEt)] and [PtIMe3(MeSCH2CH2SBut)]

Abstract

Platinum(IV) complexes of general type [PtXMe₃(RSCH₂CH₂SR′)](X = Cl, Br, or I; R = Me, R′= Et or Bu^t; R = R′= Bu^t) have been synthesised. Solid-state structures for two of the complexes (X = Cl, R = Me, R′= Et; X = I, R = Me, R′= Bu^t) have been established by X-ray crystallography. All the complexes have been extensively studied in solution by variable-temperature one- and two-dimensional n.m.r. spectroscopy. The thioalkyl dependence of the energy barriers for pyramidal sulphur inversion was found to be SMe > SEt SBu^t. At above-ambient temperatures ligand 180° rotations and PtMe₃ 120° rotations occur, these two fluxions showing high degrees of correlation.