SYNTHESIS OF NEW ORTHOMETALLATED IRIDIUM(III) COMPOUNDS BY CHEMICAL AND ELECTROCHEMICAL METHODS

Article abstract of DOI:10.1016/S0022-328X(00)99365-3

Replacement of one phosphine ligand in IrCl3(η²-PCBr)(η¹-PCBr) (1) (PCBr=P(o-BrC6F4)Ph2), by various P-donor ligands has given compounds of stoichiometry IrCl3(η²-PCBr)L (3: L=PMePh2; 4: L=P(p-MeC6H4)3; 5: L=P(OMe)3, 6: L=P(OPh)3).All of these show two irrevesible reduction peaks in the range -1.1, -1.3 and ca. -2.0 V.The electrochemical reduction of compound 1 at -1.5 V (at deg C) leads to a very reactive iridium(I) species, probably IrCl(PCBr)2, which undergoes intramolecular orthomettallation at room temperature.Three compounds are obtained as the results of this chemical conversion: IrBr2(PC)(PCBr) (7), IrCl2(PC)(PCBr) (8) and (as a mixture of isomers) IrClBr(PC)(PCBr) (9) (PC=P(C6F4)Ph2).The different behavior of rhodium and iridium complexes in these reactions are discussed.