Formation of an Azaruthenacyclopentadiene Skeleton via Ammonia Activation by an Electron-Deficient Ru 3 Cluster

A dicationic triruthenium complex containing a μ -η -C ring, [(Cp*Ru) (μ -η -C MeH -)(μ -CH)(μ-H)] (1 a, Cp*=η -C Me ), reacted with ammonia to yield a μ-amido complex, [(Cp*Ru) (μ -η -CHCMeCH) (μ -CH)(μ-NH )] (5), via N-H bond scission. Subsequent treatment with base resulted in C-N bond formation to yield a μ -η :η -1-azabutadien-4-yl complex, [(Cp*Ru) (μ -CH)(μ -η :η -NH=CH-CMe=CH-)] (6 a). The azaruthenacyclopentadiene skeleton was alternatively synthesized by the photolysis of mono-cationic complex [(Cp*Ru) (μ -η -C RH -)(μ -CH)] (2 a; R=Me, 2 b; R=H) in the presence of ammonia. The C ring skeleton was broken via the electron transfer to the π*(C-C) orbital in the C ring, and a transiently generated unsaturated μ -allylic species can take up ammonia, resulting in N-H bond scission followed by C-N bond formation.