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

Transmetallation reactions of ortho-mercurated iminophosphoranes (2-ClHgC6H4)Ph2PNR with [AuCl4]− gives new cycloaurated iminophosphorane complexes of gold(III) (2-Cl2AuC6H4)Ph2PNR [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)Ph2PNPh with PPh3 results in displacement of a chloride ligand giving the cationic complex [(2-Cl(PPh3)AuC6H4)Ph2PNPh]+, indicating that the PN donor is strongly bonded to the gold centre.

Graphical abstractTransmetallation of ortho-mercurated iminophosphoranes (2-ClHgC6H4)Ph2PNR with [AuCl4]− gives new cycloaurated iminophosphorane complexes of gold(III) (2-Cl2AuC6H4)Ph2PNR [R = (R,S)- or (S)-CHMePh, p-C6H4F, tBu]. The PN-donor ligand of (2-Cl2AuC6H4)Ph2PNPh is strongly bonded to the gold(III) centre and is not displaceable by PPh3, which gives [(2-Cl(PPh3)AuC6H4)Ph2PNPh]PF6. Thiosalicylic acid and catechol replace the chloride ligands with the dianionic chelating ligands and these derivatives show significantly higher activities against P388 murine leukaemia cells than the parent complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide