Synthesis and reactivity of gold(III) complexes containing cycloaurated iminophosphorane ligands

Transmetallation reactions of ortho-mercurated iminophosphoranes (2-ClHgC6H4)Ph2Pdouble bond; length as m-dashNR with [AuCl4]− gives new cycloaurated iminophosphorane complexes of gold(III) (2-Cl2AuC6H4)Ph2Pdouble bond; length as m-dashNR [R = (R,S)- or (S)-CHMePh, p-C6H4F, tBu], characterised by NMR and IR spectroscopies, ESI mass spectrometry and an X-ray structure determination on the chiral derivative R = (S)-CHMePh. The chloride ligands of these complexes can be readily replaced by the chelating ligands thiosalicylate and catecholate; the resulting derivatives show markedly higher anti-tumour activity versus P388 murine leukaemia cells compared to the parent chloride complexes. Reaction of (2-Cl2AuC6H4)Ph2Pdouble bond; length as m-dashNPh with PPh3 results in displacement of a chloride ligand giving the cationic complex [(2-Cl(PPh3)AuC6H4)Ph2Pdouble bond; length as m-dashNPh]+, indicating that the Pdouble bond; length as m-dashN donor is strongly bonded to the gold centre.