THE SYNTHESIS AND REACTIVITY OF ELECTROPHILIC IRIDIUM(III) COMPLEXES CONTAINING BIS(DIPHENYLPHOSPINO) ETHANE

The complex Ir(CH3) (CO)(CF3SO3)(2)(dppe) (1) has been synthesized fro m the reaction of Ir(CH3)I-2(CO)(dppe) and silver triflate. Methane an d IrH(CO)(CF3SO3)(2)(dppe) (2) are formed when a methylene chloride so lution of 1 is placed under 760 torr dihydrogen. Conductivity studies indicate that methylene chloride solutions of complexes 1 and 2 are we ak electrolytes and only partially ionized at concentrations above 1 m M. Complex 2 is an effective hydrogenation catalyst for ethylene and l -hexene while acetone hydrogenation is inhibited by the formation of [ IrH2(HOCH(CH3)(2)) (GO) (dppe)] (OTf) (3). Linear dimerization and pol ymerization of styrene occurs via a carbocationic mechanism initiated by triflic acid elimination from 2. Treatment of an acetonitrile solut ion of Ir(CH3)I-2(CO)(dppe) with silver hexafluorophosphate produces t he solvent promoted carbonyl insertion product [Ir(C(O)CH3)(NCCH3)(3)( dppe)] [PF6](2) (7) which readily undergoes deinsertion in methylene c hloride to form [Ir(CH3)(CO) (NCCH3)(2)(dppe)] [PF6](2) (8) and aceton itrile.