Reactions of Perfluoroalkyl Iodides with M(C5H5)(CO)(PMe3) [M = Rh, Ir]; Evidence for Direct Fluoroalkylation at a CO Ligand

While reaction of n -C 3 F 7 I with CpRh(PMe 3 )(CO) gives the expected product of oxidative addition, CpRh(PMe 3 )( n C 3 F 7 )(I), the analogous reaction of iso-C 3 F 7 I affords a mixture of CpRh(PMe 3 )(CF(CF 3 ) 2 )(I) and the perfluoroacyl complex CpRh(PMe 3 )(COCF(CF 3 ) 2 )(I). The latter compound is not formed from the former by a migratory insertion reaction. In further contrast, low-temperature reaction of CpIr(CO)(PMe 3 ) with n -C 3 F 7 I gives the ionic complex [CpIr(CO)(PMe 3 )( n C 3 F 7 )] + I -, which is inert to thermal substitution; treatment with N -methylmorpholine- N -oxide (NMO) results in CO oxidation and iodide coordination to give CpIr(PMe 3 )( n C 3 F 7 )(I). The same reaction at room temperature affords a mixture of four products, including small amounts of [CpIr(CO)(PMe 3 )( n C 3 F 7 )] + I - and CpIr(PMe 3 )( n C 3 F 7 )(I); the major components are the perfluoroacyl complex CpIr(PMe 3 )(CO n C 3 F 7 )(I) and the perfluoroacyl(perfluoroalkyl) complex CpIr(PMe 3 )(CO n C 3 F 7 )( n C 3 F 7 ). Crystallographic structure determinations of all these molecules are reported, and a mechanism involving direct fluoroalkylation at CO is proposed.