Reactions of co-ordinated ligands. Part 51. The reactions of σ,η3(5e)-butadienylruthenium complexes [Ru{C(Ph)-η3-C(Ph)C(Ph)CR(Ph)}(η-C5H5)](R = H or CHO) with P(OMe)3, PhCCPh, H+ and aryldiazonium cations; crystal structure of [Ru{C(O)C(Ph)C(Ph)-η2-(Z)C(Ph)CH(Ph)}{P(OMe)3}(η-C5H5)]

Abstract

Treatment of the σ,η³(5e)-butadienyl complex [Ru{C(Ph)-η³-C(Ph)C(Ph)C(Ph)CHO}(η-C₅H₅)]1 with P(OMe)₃ affords the acyl complex [Ru{C(O)C(Ph)C(Ph)-η²-(Z)-C(Ph)CH(Ph)}{P(OMe)₃}(η-C₅H₅)], structurally identified by single-crystal X-ray diffraction. This reaction involves an apparent 1,5-hydrogen shift from the aldehydic carbon to the former alkylidene carbon. Reaction of the related complex [Ru{C(Ph)-η³-C(Ph)C(Ph)CH(Ph)}(η-C₅H₅)]2 with diphenylacetylene gives [Ru(η⁵-endo-C₆Ph₆H)(η-C₅H₅)], whereas reaction of 2 with the electrophilic reagent HBF₄·Et₂O affords the 1,3-diene cationic complex [Ru{η⁴-(E,Z)-CH(Ph)C(Ph)C(Ph)CH(Ph)}{P(OMe)₃}(η-C₅H₅)][BF₄]. In contrast, protonation of the adduct formed between 2 and P(OMe)₃, the complex [Ru{C(Ph)C(Ph)-η²-C(Ph)CH(Ph)}{P(OMe)₃}(η-C₅H₅)], gives the isomeric cation [Ru{η⁴-(Z,Z)-CH(Ph)C(Ph)-C(Ph)CH(Ph)}{P(OMe)₃}(η-C₅H₅)][BF₄]. An attempt to convert 2 into a 17e cation by oxidation with p-nitrobenzenediazonium tetrafluoroborate leads instead to formation of the aryldiazenido complex [Ru{C(Ph)C(Ph)-η²-C(Ph)CH(Ph)}(p-NO₂C₆H₄N₂)(η-C₅H₅)]. The mechanisms of these reactions are discussed.