Reactions of co-ordinated ligands. Part V. The addition of tetrafluoroethylene to tricarbonyl(diene)iron, tricarbonyl(trans-cinnamaldehyde)iron, and tricarbonyl(o-styryldiphenylphosphine)iron complexes

Abstract

Tetrafluoroethylene reacts with tricarbonyl(buta-1,3-diene, trans-penta-1,3-diene, isoprene, or 2,3-dimethylbuta-1,3-diene)iron on u.v. irradiation to afford 1 : 1 adducts formulated as π-allylic iron(II) complexes, in which the C₂F₄ links the metal and diene, the linking reaction occurring preferentially at the least-substituted end of the diene. Similar reactions are observed with tricarbonyl(cyclohexa-1,3-diene or bicyclo[4.2.0]octa-1,3-diene)iron to give π-allylic adducts. The corresponding reaction with tricarbonyl(cyclo-octa-1,3-diene)iron affords two complexes, a π-allylic adduct and a tetracarbonylferracyclopentane. Tetra- and tri-carbonyl(trans-cinnamaldehyde)iron react with C₂F₄ to give tetracarbonylferracyclopentanes, in which the aldehyde and phenyl groups have a relative cis-configuration. Tricarbonyl(norbornadiene)iron and tricarbonyl(o-styryldiphenylphosphine)iron also form adducts with C₂F₄, the former giving a nortricyclene tetracarbonyl species. The n.m.r. spectra of these complexes and possible modes of formation are discussed.