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

A dicationic triruthenium complex containing a μ 3 -η 3 -C 3 ring, [(Cp*Ru) 3 (μ 3 -η 3 -C 3 MeH 2 -)(μ 3 -CH)(μ-H)] 2+ (1 a, Cp*=η 5 -C 5 Me 5 ), reacted with ammonia to yield a μ-amido complex, [(Cp*Ru) 3 (μ 3 -η 3 -CHCMeCH) (μ 3 -CH)(μ-NH 2 )] 2+ (5), via N-H bond scission. Subsequent treatment with base resulted in C-N bond formation to yield a μ 3 -η 2 :η 2 -1-azabutadien-4-yl complex, [(Cp*Ru) 3 (μ 3 -CH)(μ 3 -η 2 :η 2 -NH=CH-CMe=CH-)] + (6 a). The azaruthenacyclopentadiene skeleton was alternatively synthesized by the photolysis of mono-cationic complex [(Cp*Ru) 3 (μ 3 -η 3 -C 3 RH 2 -)(μ 3 -CH)] + (2 a; R=Me, 2 b; R=H) in the presence of ammonia. The C 3 ring skeleton was broken via the electron transfer to the π*(C-C) orbital in the C 3 ring, and a transiently generated unsaturated μ 3 -allylic species can take up ammonia, resulting in N-H bond scission followed by C-N bond formation.