Nuclear magnetic resonance investigations of configurational non-rigidity in dinuclear platinum(IV) 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 Pt^IV–S and Pt^IV–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 Pt^IV 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.