Reactivity of η2-CS3Me metal complexes as electrophiles

Abstract

The CS₂ carbon atom of the η²-CS₃Me ligand in the cobalt(II) and nickel(II) complexes [M(tppme)(S₂CSMe)][BPh₄][M = Co (1) or Ni (2), tppme = 1,1,1-tris(diphenylphosphinomethyl)ethane] is an electrophilic centre, susceptible to attack by nucleophiles such as PEt₃ and H^–; as a result the new complexes [M(tppme){S₂C(PEt₃)SMe}][BPh₄][M = Co or Ni] and [Co(tppme){S₂C(H)SMe}] are obtained. Reaction of an excess of NaBH₄ with (1) gives the complexes [Co(tppme)(S₂CS)], [Co(tppme)(η²-CS₂)](8), and [Co(tppme)(S₂CO)]. The C–SMe bond in both compounds (1) and (2) is cleaved by sodium to give the η²-CS₂ complexes (8) and [Ni(tppme)(η²-CS₂)] respectively. Replacement of the SMe group in complex (2) by NEt₂, followed by reaction of the resultant dithiocarbamate complex with NaBH₄, affords the nickel(I) thiolato-complex [Ni(tppme)(SH)], which reacts with CS₂ to give the trithiocarbonate complex [Ni(tppme)(S₂CS)]. All the products have been fully characterized. Mechanisms for the formation of the reaction products are proposed and discussed.