Metal complexes of sulphur ligands. Part V. Dialkyl-, diaryl-phosphinodithioato-and NN-dialkyldithiocarbamato-complexes of ruthenium(II)

Abstract

Complexes of general formula [Ru(S–S)₂L₂][(S–S)^–=^–S₂PR₂(R = Me, Et, Ph), ^–S₂CNMe₂; L = PPh₃, PMe₂Ph, PMePh₂, P(OPh)₃etc.] have been synthesised by the reaction of various ruthenium(II) and (III) tertiary phosphine and phosphite complexes with Na(S–S). For (S–S)^–=^–S₂PR₂, these compounds are readily carbonylated to give the monocarbonyls [Ru(S₂PR₂)₂L(CO)]. However, the dicarbonyls can be synthesised directly, from ruthenium carbonyl halides and NaS₂PR₂. Although the corresponding dithiocarbamates are resistant to carbonylation, all these compounds undergo ligand exchange reactions with ligands of greater basicity (L′) to give either [Ru(S–S)₂LL′] and/or [Ru(S–S)₂L′₂]. All these compounds have been thoroughly examined by i.r., mass, and ¹H n.m.r. spectroscopy and the latter indicates a cis-configuration. Most of these compounds also show temperature variable ¹H n.m.r. spectra, attributable to facile interconversion of optical enantiomers (for the ^–S₂PR₂ compounds), restricted rotation about the –CN bond (for the ^–S₂CNMe₂ compounds), and, in some cases, hindered rotation about the ruthenium–phosphorus bonds.

Finally, for [Ru(S₂PR₂)₂(PMe₂Ph)₂], carbonylation gives, in addition to [Ru(S₂PR₂)₂(PMe₂Ph)CO], two isomers of formula [Ru(S₂PR₂)₂(PMe₂Ph)₂CO]. The structures of these compounds have been established by ¹H, ³¹P n.m.r., and double resonance studies and a general mechanism of carbonylation for these compounds is proposed.