A dynamic nuclear magnetic resonance study of trimethylplatinum(IV) halide complexes of 1,1,2,2-tetrakis(methylthio)ethane. Part 3. Structure and fluxionality of dinuclear complexes [(PtXMe3)2{(MeS)2CHCH(SMe)2}]

Abstract

Dinuclear platinum(IV) complexes [(PtXMe₃)₂{(MeS)₂CHCH(SMe)₂}] were prepared by treating the mononuclear chelate complexes [PtXMe₃{(MeS)₂CHCH(SMe)₂}] with equimolar amounts of [(PtXMe₃)₄](X = Cl, Br, or I). In the new complexes the ligand acts as a double chelate towards the PtXMe₃ moieties. The most likely static solution structures of these complexes are deduced from n.m.r. evidence. Low-temperature ¹H n.m.r. bandshape analysis yielded pyramidal inversion energies of the co-ordinated S atoms [ΔG^‡(298.15 K)= 57–59 kJ mol^–1] and high-temperature two-dimensional exchange spectroscopy n.m.r. spectra yielded energies associated with the Pt-methyl scrambling fluxion [ΔG^‡(298.15 K)= 90–92 kJ mol^–1].