Synthesis of platinum(II) and palladium(II) complexes containing substituted (2-aminophenyl)phosphines. Molecular structure of cis-[PtMe(2-HNC6H4PPh2)(2-H2NC6H4PPh2)]

Abstract

Bis(unidentate ligand)platinum(II) complexes of the type cis-[PtMe₂L₂] (where L = 2-H₂NC₆H₄PPhR and R = H, Me or Ph) were readily formed upon reaction of [PtMe₂(cod)] (cod = cycloocta-1,5-diene) with L in n-pentane. The neutral ligand L is co-ordinated via the phosphorus donor atom. The complex cis-[PtMe₂(2-H₂NC₆H₄PPh₂)₂] underwent a novel, facile rearrangement in benzene to give cis-[PtMe(2-HNC₆H₄PPh₂)(2-H₂NC₆H₄PPh₂)] with concomitant loss of methane. The molecular structure of the demethylated complex has been confirmed by an X-ray analysis. Mono(bidentate ligand)platinum(II) complexes of the type [PtCl(Me)L] (where L = 2-H₂NC₆H₄PPhR and R = Me or Ph) have been prepared by treating the appropriate ligand with [PtCl(Me)(cod)] in dichloromethane. Further reaction with HCl gave the dichloroplatinum(II) complexes [PtCl₂L]. Substitution of the chloro groups in [MCl₂L] (where M = Pd^II or Pt^II, L = 2-H₂NC₆H₄PPhR and R = Me or Ph) can be achieved by reaction with silver nitrate in acetonitrile followed by the addition of sodium oxalate to give the complexes [M(C₂O₄)L]. These mono(bidentate ligand) complexes are seen as potential anticancer agents. Preliminary biological studies have shown them to be active against the mouse tumour model P815 in vitro with cytotoxicities of certain of these complexes being comparable to that of cisplatin, cis-[PtCl₂(NH₃)₂].