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.