Oxidative Addition of Functionalized Alkyl-Halides to Iridium(I) Complexes IrCl(Co)L2 (L = PMe2Ph2>, IrCl(Co)PMe3)

Iridium(I) complexes IrCl (CO)L2 (L = PMePh2, PMe2Ph, PMe3) oxidatively add alkyl bromides RBr bearing electron-withdrawing substituents on the α-carbon atom (R = CH2CO2Et,CH3CHCO2Et,CH3CHCOCH3,C2H5CHNO2) to give octahedrally coordinated alkyliridium (III) complexes IrBrClR (CO)L2, for which 1H and 31P n.m.r . data are reported. In the secondary alkyls, the mutually trans tertiary phosphine ligands are inequivalent, consequently the P-Me resonance is not the usual 1 : 2 : 1 'virtual' triplet. In some cases the pattern is a doublet or a doublet of doublets, similar to that expected for mutually cis tertiary phosphine ligands . In contrast to simple s- alkyliridium (III) complexes, the functionalized s-alkyls do not isomerize under any conditions to the corresponding n-alkyls, and the reverse process does not occur for n-alkyls such as IrBrCl (CH2CH2CO2Et)(CO)(PMe3)2 and IrClI (CH2CH2CN)(CO)(PMe3)2. Diiodomethane and chloroiodomethane readily add to IrCl (CO)L2 to give haloalkyliridium (III) complexes IrClI (CH2Y)(CO)L2(Y = Cl , I). These contain mutually trans tertiary phosphine ligands , although in the case of L = PMe2Ph unstable cis - isomers can be detected. Attempts to form complexes containing Ir - CHBrCH3 or Ir -CH(OC2H5)CH3 by addition of CH3CHBr2 or CH3CHClOC2H5 to IrCl (CO)(PMe3)2 gave only IrBr2Cl(CO)(PMe3)2 and IrHCl2(CO)(PMe3)2, respectively.