Skeletal Rearrangement of a C<INF>2</INF> Unit on a Triruthenium Cluster. Synthesis of μ-Ethylidene, μ<INF>3</INF>-Ethylidyne, and μ<INF>3</INF>-Vinylidene Complexes by the Reaction of {Cp*Ru(μ-H)}<INF>3</INF>(μ<INF>3</INF>-H)<INF>2</INF> with Acetylene

Reaction of the triruthenium pentahydride complex {Cp*Ru(μ-H)}<INF>3</INF>(μ<INF>3</INF>-H)<INF>2</INF> (<BO>1</BO>; Cp* = η⁵-C<INF>5</INF>Me<INF>5</INF>) with acetylene was investigated, in which the μ<INF>3</INF>-ethylidene−μ<INF>3</INF>-η²(∥)-ethyne complex {Cp*Ru(μ-H)}<INF>3</INF>(μ-CMeH){μ<INF>3</INF>-η²(∥)-CH&dbd;CH} (<BO>2</BO>) was produced via formation of the intermediary bis(μ-vinyl) complex {Cp*Ru(μ-H)}<INF>3</INF>(μ-η¹:η²-CH&dbd;CH<INF>2</INF>)<INF>2</INF> (<BO>3</BO>). An α-C−H bond of the μ-ethylidene ligand of <BO>2</BO> underwent oxidative addition upon thermolysis to yield the μ<INF>3</INF>-ethylidyne−μ<INF>3</INF>-η²(∥)-ethyne complex (Cp*Ru)<INF>3</INF>(μ-H)<INF>2</INF>(μ<INF>3</INF>-CCH<INF>3</INF>){μ<INF>3</INF>-η²(∥)-CH&dbd;CH} (<BO>5</BO>), which showed fluxional behavior of both the μ<INF>3</INF>-ethyne and the hydride ligands. Further C−H bond cleavage of the μ<INF>3</INF>-ethylidyne ligand, affording the μ-vinylidene−μ<INF>3</INF>-η²(∥)-ethyne complex (Cp*Ru)<INF>3</INF>(μ-H)(μ<INF>3</INF>-C&dbd;CH<INF>2</INF>){μ<INF>3</INF>-η²(∥)-CH&dbd;CH} (<BO>6</BO>), was also investigated. Treatment of <BO>5</BO> with an excess amount of acetylene resulted in C−C bond formation at the Ru<INF>3</INF> core, and the μ<INF>3</INF>-ethylidyne−μ<INF>3</INF>-η³-diruthenaallyl complex (Cp*Ru)<INF>3</INF>{μ<INF>3</INF>-η¹:η³:η¹-C(H)C(H)CCH<INF>3</INF>}(μ<INF>3</INF>-CCH<INF>3</INF>)(μ-H) (<BO>7</BO>) was obtained. The molecular structures of <BO>5 </BO>and<BO> 7</BO> were determined by single-crystal X-ray diffraction studies.