Towards thermally robust homogeneous catalysts: Re, Ir and W complexes of the highly thermally stable ligand, tri-2-pyridylamine

Abstract

The ligand tri-2-pyridylamine (tripyam (1)), which was expected to be highly resistant to thermal degradation, forms a variety of stable complexes with rhenium, tungsten and iridium. Reaction of 1 with ReCl3(PPh3) (benzil), WCl4(PPh3)2 and (NH4)2IrCl6 yields the chloride complexes ReCl3(tripyam) (2), WCl4(tripyam) (3) and IrCl3(tripyam) (4), respectively. In addition, the first tripyam supported hydride, [IrH2(PPh3)2(η2-tripyam)]BF 4 (5), was synthesized by reaction of 1 with the dihydride [IrH2(PPh3)2(acetone)2]BF 4. The principal characteristic of 2, 4 and 5 is their very high thermal stability: they survive thermolysis at temperatures up to 270°C. Finally, the high oxidation state complexes [ReO3(tripyam)]ReO4 (6) and [ReO(OCH2CH2O) (PPh3) (tripyam)]Cl (7) were also synthesized.