Iridium complexes of tertiary t-butyl- and di-t-butylphosphines including some five-co-ordinate iridium(III) complexes with hydride resonances at τca. 60
Treatment of chloroiridous acid with di-t-butyl-n-alkylphosphines (4 mol. equivalents) in boiling isopropyl alcohol gives purple, five-co-ordinate, square pyramidal hydrides [IrHCl2(PBut2R)2](R = Me, Et, or Prn). These complexes have a hydride resonance at τca. 60, the highest yet observed. With 2 or 3 mol. equivalents of PBut2Prn in isopropyl alcohol, chloroiridous acid gives [PBut2PrnH][Ir2Cl7(PBut2Prn)2] but with 2 equivalents of PBut2Me a hydride is formed, possibly [PBut2MeH][Ir2HCl6(PBut2Me)2]. With primary alcohols as solvents, hydride formation is generally accompanied by abstraction of carbon monoxide from the alcohol; thus chloroiridous acid and t-butyldi-n-propylphosphine in 2-methoxyethanol eventually give a mixture of trans-[IrCl(CO)(PButPrn2)2] and [IrHCl2(CO)(PButPrn2)2] in very high yield. [IrHCl2(PBut2Prn)2] reacts with boiling 2-methoxymethanol to give trans-[IrCl(CO)(PBut2Pr n2)2] in 90% yield. 1H- and 31P-N.m.r. and i.r. data are given.