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 IrCl_3′[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.