Reactions of coordinated ligands. Part 47. Synthesis, structure, and reactivity of [.eta.4(5e)-butadienyl]ruthenium complexes: crystal structures of CpRu:C(Ph)-.eta.3-[C(Ph)C(Ph)CH(Ph)], CpRuC(Ph):C(Ph)-.eta.2-[C(Ph):CH(Ph)]P(OMe)3, and CpRu2[.mu.-(Z)-C(Ph):CH(Ph)](CO)2(.eta.4-C4Ph4)