Metal complexes of sulphur ligands. Part VI. Studies of facile optical isomerism reactions in dimethylphosphinodithioato-complexes of ruthenium(II)

Abstract

Rate constants and associated activation parameters for the optical isomerisation reactions of cis-[Ru(S₂PMe₂)₂L₂][L = PPh₃, PMePh₂, PMe₂Ph, P(OMe)₃, P(OPh)₃], cis-[Ru(S₂PMe₂)₂(PPh₃)(P{OPh}₃)] and cis-[Ru(S₂PMe₂)₂(PPh₃)CO] have been determined by line-shape analyses of their temperature-dependent ¹H n.m.r. spectra. Consideration of various bond-rupture and twist mechanisms for this inversion process strongly suggests that the only mechanism compatible with the overall experimental data is one involving a solvent-assisted cleavage of a ruthenium–sulphur bond trans to L.

For the analogous cis-[Ru(S₂CNMe₂)₂L₂][L = PPh₃, PMe₂Ph, P(OPh)₃] and cis-[Ru(S₂CNMe₂)₂(PPh₃)(P{OPh}₃)] complexes, line shape studies suggest that their temperature dependent ¹H n.m.r. spectra arise from restricted rotation about the CN bonds and not a facile inversion process.