Metal complexes of sulphur ligands. Part 18. Reaction of tris- and tetrakis-(tertiary phosphine)dichlororuthenium(II) complexes with various dithioacid ligands

Abstract

Reaction of [RuCl₂L₄][L = PPh(OMe)₂ or PMePh₂] and [RuCl₂(PEtPh₂)₃] with various alkali-metal dithioacid salts gives, under all conditions, the complexes [Ru(S–S)₂L₂][S–S = S₂PR′₂(R′= Me or Ph), S₂COMe, or S₂CNR′₂(R′= Me or Et)]. In contrast, the products of reaction of cis-[RuCl₂(PMe₂Ph)₄] and [RuCl₂{PPh₂(OR)}₃](R = Me or Et) with these dithioacid anions are very sensitive to reaction conditions. For example, shaking with Na[S₂PR′₂] in benzene gives the yellow complexes [RuCl(S₂PR′₂)L₃] which readily rearrange to the red five-co-ordinate cations [Ru(S₂PR′₂)L₃]⁺ in alcoholic media. In contrast, shaking with K[S₂COMe] gives the six-co-ordinate [Ru(S₂COMe)₂L₃](with uni- and bi-dentate S₂COMe co-ordination), which on heating rearrange irreversibly to [Ru(S₂COMe)₂L₂]. Reaction of [RuCl₂(PMe₂Ph)₄] with Na[S₂CNR′₂]·×H₂O for very short periods in ethanol gives [Ru(S₂CNR′₂)(PMe₂Ph)₄]⁺, whereas in benzene [Ru(S₂CNR′₂)₂(PMe₂Ph)₃] are formed. All these complexes have been fully characterised by elemental analyses and ¹H and ³¹P-{¹H} n.m.r. spectroscopy, and a general mechanism for the formation of [Ru(S–S)₂L₂] from [RuCl₂L_n](n= 3 or 4) is proposed.