Intramolecular carbon–carbon coupling reactions of a κ2(P,P)-bis(diphenylphosphino)methanide ligand with unsaturated carbene moieties in indenyl–ruthenium(II) complexes

Treatment of disubstituted indenyl–ruthenium(II) vinylidene complexes [Ru{CC(Me)R}(η5-C9H7)(dppm)][CF3SO3] (R=tBu (4a), Ph (4b); dppm=bis(diphenylphosphino)methane) with NaOMe results in the deprotonation of the coordinated dppm ligand to give a κ2(P,P)-(Ph2P)2CH ligand. Subsequent intramolecular nucleophilic attack of the methanide group on the electrophilic vinylidene α-carbon gives the alkenyl metallacycles (Z)-[Ru{κ3(C,P,P)-C̄HPPh2)}(η5-C9H7)] (R=tBu (6a), Ph (6b)). The related metallacycle species [Ru{κ3(C,P,P)-C(OMe)C(H)HPPh2)}(η5-C9H7)] (R=H (11a), Ph (11b)) have also been prepared. They have been obtained through an analogous carbon–carbon coupling process involving the bis(phenyl-phosphino)methanide anion, generated by the treatment of the α,β-unsaturated methoxy–carbene derivatives [Ru{C(OMe)C(H)C(H)R}(η5-C9H7)(dppm)][PF6] (R=H (9a), Ph (9b)) and LitBu, and the Cγ atom of the unsaturated carbene ligand.