Nuclear magnetic resonance investigations of configurational non-rigidity in dinuclear platinum(<scp>IV</scp>) complexes. Part 4. Ring reversal, pyramidal inversion, and novel fluxional rearrangements in [(PtXMe₃)₂(MeSCH₂SeMe)] complexes

Abstract

Dinuclear complexes of the type DL-[(PtXMe3)2(MeSCH2SeMe)] containing both PtIV–S and PtIV–Se bonds have been isolated. Detailed variable-temperature n.m.r. studies have established the existence of ligand ring reversal, pyramidal inversion of both S and Se atoms, ligand commutation (switching) between Pt atom pairs and scrambling of the platinum methyl environments which is considered to be a consequence of rapid ligand commutation producing a highly non-rigid seven-co-ordinate PtIV intermediate. Accurate energy barriers for these non-dissociative dynamic processes have been computed. Despite the probable non-synchronous nature of the S/Se double inversion, the spectra are shown to be sensitive only to Se inversion.