HALOGENOTRIMETHYLPLATINUM(IV) COMPLEXES OF 2,6-BIS(P-TOLYLTHIOMETHYL)PYRIDINE (L1) - NUCLEAR-MAGNETIC-RESONANCE STUDIES OF THEIR SOLUTION-STATE STEREODYNAMICS AND THE CRYSTAL-STRUCTURE OF FAC-[PTBRME3L1]

Under mild conditions 2,6-bis(p-tolylthiomethyl)pyridine (L1) reacted with halogenotrimethylplatinum(IV) to afford complexes of the type fac-[PtXMe3L1] (X = Cl or Br). This potentially terdentate ligand acts here in a five-membered S/N chelate bidentate fashion. Solution dynamic NMR studies revealed the presence of three fluxional processes: pyramidal inversion of the co-ordinated sulfur atom, S-S switching with correlated pyramidal inversion, and S-S switching. The mechanism for the S-S exchange process was elucidated by two-dimensional NMR exchange spectroscopy. The crystal structure of fac-[PtBrMe3L1] confirms the bidentate chelate nature of the ligand in the solid state, with a N-Pt-S(1) angle of 81.5-degrees. IR data for the Pt-C, Pt-N and Pt-X stretching modes in these complexes are also presented.