Reactions of co-ordinated ligands. Part VII. Tetrafluoroethylene with π-allyliridium(I) complexes
Abstract
Reaction of tetrafluoroethylene with [Ir(π-allyl)(CO)L2](L = PPh3 or AsPh3; allyl = C3H5, 1-MeC3H4, or 2-MeC3H4) affords the iridium(III) species [[graphic omitted]F2(π-allyl)(CO)L]. The corresponding reaction of [Ir(π-2-MeC3H4)(CO)(diphos)] gives [[graphic omitted]F2(σ-2-MeC3H4)(CO)(diphos)]. These iridium(III) complexes do not undergo insertion reactions on treatment with carbon monoxide or phosphine. However, reaction with C2F4 at 80 °C affords the insertion products [[graphic omitted]CH2(CO)(L)](L = PPh3 or AsPh3) and [[graphic omitted]CHMe(CO)(PPh3)], the latter complex existing in solution as isomers which inter-convert by olefin rotation. Carbon monoxide or triphenylphosphine readily displace C2F4 from these systems to give [[graphic omitted]CH2(CO)2(PPh3)] and [[graphic omitted]CH2(CO)(PPh3)2]. In contrast, reaction of [[graphic omitted]F2(π-C3H5)(CO)(PPh3)] with an excess of C2F4 affords an unusual iridabicyclo[3.3.0]octane, the metal being sited at the ring junction. The n.m.r. spectra and mechanism of formation of these complexes are discussed.