Complexes of osazones with palladium(II) and platinum(II): isomerization, oxidation, and ortho-metallation of the co-ordinated ligands

Abstract

The preparation, properties, and reactions of a series of complexes of general formula [MCl₂(L)] are described for the first time (M = Pt) or reinvestigated (M = Pd)[L = Ph(H)N·N:[graphic omitted]:N·N(H)Ph (L¹), Ph(H)N·N:C(Me)·C(Me):N·N(H)Ph (L²), and Ph(Me)N·N:C(Me)·C(Me):N·N(Me)Ph (L³)]. On treatment with base, complexes of L¹ and L² readily undergo hydrogen-chloride elimination to give species of formula [{MCl(L – H)}_x] which contain a covalent M–N bond. These complexes in solution undergo further transformation with loss of a hydrogen molecule and formation of ortho-metallated diazoalkene derivatives, [M(L – 3H)Cl]. The complex [PtCl₂(L³)], on treatment with silica gel or refluxing in nitromethane, affords, as the palladium analogue, the cyclometallated species [PtCl(L³– H)]. The reactivities of the ligands with palladium and platinum fire compared.