Trinuclear benzene clusters of ruthenium and osmium

Abstract

The activated cluster [Os₃(CO)₇(µ₃-η²:η²:η²-C₆H₆)(C₂H₄)(MeCN)] reacts with alkynes RC₂R′(R = R′= H, Ph or Me; R = H, R′= Ph; R = Me, R′= Et) to produce the new clusters [Os₃(CO)₇(η⁶-C₆H₆)(µ₃-η²-RC₂R′)] in which the benzene molecule has migrated to a single osmium atom. In contrast, reaction of the ruthenium cluster [Ru₃(CO)₉(µ₃-η²:η²:η²-C₆H₆)] with similar alkynes RC₂R′(R = R′= H, Ph or Me; R = Ph, R′= H) yields the new clusters [Ru₃(CO)₇(η⁶-C₆H₆)(µ₃-η²-RC₂R′CO)] in which carbonyl insertion has occurred. The molecular structures of [Os₃(CO)₇(η⁶-C₆H₆)(µ₃-η²-C₂Me₂)] and of [Ru₃(CO)₇(η⁶-C₆H₆)(µ₃-η²-PhC₂PhCO)] have been established by single-crystal X-ray analysis. The C₆H₆ ligand is η⁶-bonded to a single metal atom, while the C₂Me₂ and the PhC₂PhCO ligands lie above the metal triangles and are bonded to the three metal atoms via two σ interactions and one π interaction.