Syntheses and Reactivity Studies of the Carbido-Alkylidyne Cluster Complexes LWRu₄(μ₅-C)(μ-CPh)(CO)₁₂ and LWRu₅(μ₆-C)(μ-CPh)(CO)₁₄, L = Cp and Cp*, Obtained from Reversible Scission of Acetylide Ligand

Treatment of a 1:1 mixture of Ru₃(CO)₁₂ and the acetylide cluster LWRu₂(CO)₈(C₂Ph) (1, L = Cp and Cp*) in hydrocarbon solvents afforded two carbido-alkylidyne cluster complexes, LWRu₄(μ₅-C)(CO)₁₂(μ-CPh) (2) and LWRu₅(μ₆-C)(CO)₁₄(μ-CPh) (3). Complexes 2 contain a square pyramidal cluster skeleton with a μ₅-carbide and an accompanying bridging alkylidyne ligand, while WRu₅ complexes 3 possess a distorted octahedral WRu₅(μ₆-C) framework. The transformation from 1 to 2 and 3 illustrates a reversible cleavage of an acetylide carbon−carbon bond induced by the cluster-building reaction. Moreover, the hydrogenation of complexes 2 and 3 was found to depend on the ancillary ligand on the W atom, showing selective formation of only two hydride complexes, CpWRu₄(μ₅-C)(μ-CPh)(μ-H)₂(CO)₁₁ (4) and Cp*WRu₅(μ₆-C)(μ-CPh)(μ-H)₂(CO)₁₃ (5), respectively. Single-crystal X-ray analysis on complex 4 indicated that the hydrides resided near the apical Ru atom, while the hydrides in complex 5 were associated with the unique W metal atom. Finally, treatment of 2 with thiophenol has led to formation of the wingtip-bridged butterfly complexes LWRu₄(μ₅-C)(μ-CPh)(μ-H)(μ-SPh)(CO)₁₁ (7a, L = Cp; 7b, L = Cp*), in which the thiolate ligand is bonded to the Ru atoms separated by a nonbonding distance of 3.4186(8) Å.