Gold complexes derived from diphenyl-2-styrylphosphine

Complexes of diphenyl-2-styrylphosphine (sp) with gold, first reported in 1 971, have been reinvestigated. [AuX(sp)] can be oxidised with X-2 for X = C l or Br but not for X = I. The initial product, [AuX3(sp)], undergoes a rev ersible rearrangement in which an Au-X bond adds across the styryl double b ond to give [AuX2(sp-X)] (sp-X = 2-CH(CH2X)C6H4PPh2). The carbon-bound hali de can be replaced by methoxy by reaction with methanol. [AuX2(sp-Y)] (X = Cl or Br; Y = Cl, Br or OMe) react with iodide to give eventual reduction t o [AuI(sp)], confirming that non-chelated [AuX2(Y)(sp)] is unstable when X = I. Reduction reactions of this type complicate attempts to study halide-s ubstitution reactions of [AuX2(sp-Y)], but a variety of substituted product s have been identified (e.g. those in which X = OAc CN, SCN, 1/2SCH(2)CH(2) NH(2) or 1/2S(2)CNEt(2)). Monosubstitution has been achieved with PPh2R (R = Me or Ph). The crystal structure of [Au(SCH2CH2NH2)(sp-OMe)]PF6 has been determined; in it and all other substituted products the softer, incoming l igand is trans to phosphorus.