Selective Synthesis of Indenylruthenium(II) Vinylvinylidene Complexes via Unstable Allenylidene Intermediates: Unexpected Formation of Alkenyl−Phosphonio Complexes (E)-[RuC(H)C(PPh3)R(η5-C9H7)(PPh3)2][PF6] (R = 1-Cyclohexenyl, 1-Cycloheptenyl) through Nucleophilic Addition of Triphenylphosphine on Vinylvinylidene Derivatives | Publicación