INTRAMOLECULAR COMBINATION OF VINYL, ARYL AND CARBONYL LIGANDS IN RUTHENIUM(II) COMPLEXES - A MECHANISTIC STUDY

Complexes [Ru(CO)(2)(CH=CHR)(C(6)H(4)X-4)L(L')][R = Ph, CMe(3), H, Me or OEt; X = H, Cl or OMe; L = L' = PMe(2)Ph, PMe(3), P(OMe)(2)Ph or PP h(3); L = PMe(3), L' = PPh(3)] underwent competing isomerisation react ions, one an intramolecular construction of a vinyl aryl ketone which remains co-ordinated, the other a simple redistribution of the ligands around the metal. Product ratios are determined by kinetic rather tha n thermodynamic factors. For a sequence of complexes with L = L' = PMe (2)Ph, electron-releasing substituents on the vinyl ligand favour form ation of ketone complexes, whereas similar substituents on the phenyl ligand have the reverse effect. Increasing the reaction temperature di sfavours ketone complex formation. Mechanisms involving initial migrat ion of either the vinyl or the aryl ligand are discussed on the basis of these results and a complementary study involving trapping of the l ikely acyl intermediates.