Synthesis of Platinum Complexes Containing Bidentate N,O-donor Ligands

Abstract

The reaction of N,O-donor ligands hippuric acid and N-phenylanthranilic acid with [PtCl₂(COD)] (COD = 1,5-cyclooctadiene) in dichloromethane and in the presence of silver(I) oxide yields the complexes [Pt{OC(O)CH₂N(COPh)}(COD)] and [Pt{OC(O)(C₆H₄)N(Ph)}(COD)]. Several ligand-substitution reactions were performed using complex [Pt{OC(O)CH₂N(COPh)}(COD)] and a variety of phosphines, to produce [Pt{OC(O)CH₂N(COPh)}(PPh₃)₂].1.5.CH₂Cl₂, [Pt{OC(O)CH₂N(COPh)}(dppe)][dppe = 1,2-bis(diphenylphosphino)ethane], [Pt{OC(O)CH₂N(COPh)}(PTA)₂] (PTA = 1,3,5-triaza-7-phosphaadamantane) and [Pt{OC(O)CH₂N(COPh)}(dppf)] [1,1’-bis(diphenylphosphino)ferrocene]. The X-ray crystal structure of [Pt{OC(O)CH₂N(COPh)}(COD)] was obtained which showed the hippurate ligand coordinated to platinum via the nitrogen and oxygen atoms. Attempts were made to synthesise two N,O-coordinated gold(III) complexes, however characterisation showed the resulting products to be a mixture of compounds. All new complexes were characterised by elemental analysis, melting point, electrospray ionisation mass spectrometry (ESI-MS), nuclear magnetic resonance (NMR) and infra-red (IR) spectroscopy. In particular, a range of various 1D (¹H, ¹³C, ³¹P, DEPT and selective NOESY) and 2D (COSY, NOESY, HSQC, HMBC and H2BC) NMR experiments were used to provide full spectral assignment of each complex.