Skeletal Rearrangement of a Triruthenium mu_3(perpendicular)-Alkyne Complex via the formation of a mu_3-Vinylidene Intermediate

摘要

Over the past ten years we have shown that the triruthenium complex, {Cp*Ru(mu-H)}_3(mu_3-H)_2 (1, Cp* = eta~5-C_5Me_5), effectively activates various hydrocarbons in a unique manner as a result of cooperative action of the triruthenium centers. We have previously shown that 1 reacted with linear alkanes to yield a closo-ruthenacyclopentadiene complex, (Cp*Ru)_2 {Cp*Ru-(mu-eta~4:eta~4-CR=CH-CH=CH-)}(mu-H) (2) (eq. 1). During this reaction, a mu_3(perpendicular)-alkyne complex, {Cp*Ru(mu-H)}_3(mu_3-eta~2:eta~2-(perpendicular)-RCCH) (3), was detected as an intermediate. We report herein the equilibrium between mu_3(perpendicular)-alkyne complex 3 and mu_3-vinylidene complex, {Cp*Ru(mu-H)}_3(mu_3-eta~2-C=CRH) (4), at elevated temperature (Scheme 1). This equilibrium is strongly influenced by the size of the substituent on the C_2 moiety. And, reactivity of 4 with small molecules is also mentioned.