Complexes of 2-diphenylphosphinobenzenethiol and 2-diphenylphosphino-6-trimethylsilylbenzenethiol with rhodium and iridium. Crystal and molecular structures of [IrCl2(Ph2PC6H4S)(PMePh2)2] and [Ir(Ph2PC6H4S)3]·0.75CH2Cl2

Abstract

The reaction between [IrCl3(PMePh2)3] and 2-diphenylphosphinobenzenethiolate in methanol yielded only [IrCl2(Ph2PC6H4S)(PMePh2)2]1 whereas, with IrCl3′[Ir(Ph2PC6H4S)3]2 was formed. The crystal structures of 1 and 2 have been determined. They reveal octahedral geometries about Ir with a mer arrangement of P donors in both cases. A similar reaction using [RhCl(PPh3)3] as precursor gave an analogous rhodium complex which exists as a mixture of isomers in solution with mer and fac P donors. However, with the sterically demanding 2-Ph2P(6-Me3Si)C6H3SH the complexes [M{Ph2-P(Me3Si)C6H3S}3](M = Rh or Ir) were generated. Their 31P NMR spectra indicate that these are single species with different structures from those of the Ph2PC6H4S complexes. The reaction between [IrCl(CO)(PPh3)2] and the two thiols (HL) yielded the hydride complexes [IrH(CO)L2] the 1H and 31P NMR and IR spectra of which confirmed the presence of the hydride ligand and trans-P atoms. The Ph2PC6H4S complex isomerises slowly in the solid state and in solution to a species with cis-P atoms.