Reactions of five-co-ordinate iridium(III) hydrides of type [IrHCl2(PBut2R)2](R = Me, Et, or Prn) with π- or σ-bonding ligands and with dihydrogen

Abstract

Five-co-ordinate complexes of type [IrHCl₂(PBu^t₂R)₂](R = Me, Et, or Prⁿ) readily take up CO or MeNC(Q) to give six-co-ordinate complexes, [IrHCl₂Q(PBu^t₂R)₂] where Q = less bulky tertiary phosphine. [IrHCl₂(PBu^t₂Me)₂] will also take up pyridine, 4-methylpyridine, or P(OMe)₃ to give adducts [IrHCl₂(PBu^t₂Me)₂Q] but with [IrHCl₂(PBu^t₂R)₂](R = Et or Prⁿ) these ligands displace a PBu^t₂R ligand to give [IrHCl₂Q₂(PBu^t₂R)]. We have studied the relative affinities of NH₃, P(OMe)₃, pyridine, 2-methylpyridine, 2,6-dimethylpyridine, dimethyl sulphide, or diethylamine for [IrHCl₂(PBu^t₂Et)₂] spectrophotometrically: the first three have strong affinity, the last three very little affinity, and 2-methylpyridine intermediate affinity. [IrHCl₂(PBu^t₂Prⁿ)₂], in the presence of sodium isopropoxide takes up dihydrogen to give [IrH₅(PBu^t₂Prⁿ)₂] which in turn reacts with carbon monoxide to give [IrH₃(CO)(PBu^t₂Prⁿ)₂]. I.r. and ¹H and ³¹P n.m.r. data are given and discussed.