Reactivity of η2-trithiocarbonate metal complexes as nucleophiles. Intramolecular mobility of the trithiocarbonate group in µ-CS3 binuclear complexes

Abstract

The reactivity of the trithiocarbonate nickel(II) complex [Ni(tppme)(S₂CS)](1)[tppme = 1,1,1-tris(diphenylphosphinomethyl)ethane] toward a series of electronically and co-ordinatively unsaturated metal–ligand moieties has been investigated; as a result, the homo- and hetero-metal complexes [(tppme)Ni(µ-CS₃)Ni(tppme)][BPh₄]₂(2), [(tppme)Ni(µ-CS₃)Co(tppme)][BPh₄]₂(3), and [(tppme)Ni(µ-CS₃)Cr(CO)₅](4) have been synthesized. Complex (2) gives a temperature-dependent ³¹P-{¹H} n.m.r. spectrum indicative of fluxional behaviour. This is due both to the rotation of the bridging CS₃ group and to a tppme ligand, which displays an unco-ordinated phosphorus atom. The reaction of (1) with [V(η-C₅H₅)2] results in the formation of the nickel(0)η²-CS₂ complex [Ni(tppme)(η²-CS₂)] through sulphur abstraction from the η²-CS₃ ligand. The further reactivity of the binuclear complexes toward NaBH₄ has been investigated. The chemical analogies between η²-CS₃ and η²-CS₂ metal complexes are discussed.