Synthesis and single-crystal X-ray diffraction studies of new cyclometallated phenylimidazole palladium(II) compounds

Cyclometallation of 1,4,5-trimethyl-2-phenylimidazole, L, with Pd(OAc)(2) gave exclusively the dinuclear anti isomer with bridging acetate ligands, 1. Subsequent treatment of 1 with sodium chloride gave the corresponding dinuclear compound with bridging chloride ligands, 2. Treatment of 2 with mono or diphosphanes led to partial or total bridge-splitting reactions, yielding mono or polynuclear compounds, 3-9, depending on the palladium/phosphane ratio and the nature of the phosphane. The structure of 7 has been determined by X-ray diffraction analysis. Compounds 1 and 2 react with triphos to give the mononuclear compound, 10, in which the phosphane acts as a terdentate ligand. The crystal structure of 10 confirms the pentacoordination of the palladium(II) centre, involving a long Pd-N interaction.