The synthesis and reactivity of electrophilic iridium (III) complexes containing bis (diphenylphosphino) ethane

Abstract

Abstract The complex Ir(CH 3 ) (CO) (CF 3 SO 3 ) 2 (dppe) ( 1 ) has been synthesized from the reaction of Ir(CH 3 )I 2 (CO) (dppe) and silver triflate. Methane and IrH(CO) (CF 3 SO 3 ) 2 (dppe) ( 2 ) are formed when a methylene chloride solution of 1 is placed under 760 torr dihydrogen. Conductivity studies indicate that methylene chloride solutions of complexes 1 and 2 are weak electrolytes and only partially ionized at concentrations above 1 mM. Complex 2 is an effective hydrogenation catalyst for ethylene and 1-hexene while acetone hydrogenation is inhibited by the formation of [IrH 2 (HOCH(CH 3 ) 2 ) (CO) (dppe)] (OTf) ( 3 ). Linear dimerization and polymerization of styrene occurs via a carbocationic mechanism initiated by triflic acid elimination from 2 . Treatment of an acetonitrile solution of Ir(CH 3 )I 2 (CO) (dppe) with silver hexafluorophosphate produces the solvent promoted carbonyl insertion product [Ir(C(O)CH 3 ) (NCCH 3 ) 3 (dppe)] [PF 6 ] 2 ( 7 ) which readily undergoes deinsertion in methylene chloride to form [Ir(CH 3 ) (CO) (NCCH 3 ) 2 (dppe)] [PF 6 ] 2 ( 8 ) and acetonitrile.