Reactions of a Triruthenium Pentahydrido Complex with Imines Leading to the Formation of a Perpendicularly Coordinated Iminoacyl Ligand and the Scission of a C═N Bond on a Triruthenium Plane

Abstract

The reaction of a triruthenium pentahydrido complex, {Cp*Ru(μ-H)}3(μ3-H)2 (1; Cp* = η5-C5Me5), with N-benzylidenemethylamine resulted in the exclusive formation of a perpendicularly coordinated iminoacyl complex, (Cp*Ru)3(μ-η2:η2(⊥)-PhCNMe)(μ-H)2 (3b), as a result of C–H bond scission of imine. However, the treatment of 1 with N-benzylideneaniline at 100 °C caused C–N bond cleavage to yield the μ3-benzylidyne−μ3-phenylimido complex (Cp*Ru)3(μ3-CPh)(μ3-NPh)(μ-H)2 (7c) and the μ3-methylidyne−μ3-phenylimido complex (Cp*Ru)3(μ3-CH)(μ3-NPh)(μ-H)2 (8). The formation of 7c is in strong contrast to the C–N bond scission occurred in (Cp*Ru)3(μ-η2:η2(⊥)-PhCNH)(μ-H)2 (3a), which required heating at 180 °C. The structural and spectral properties of μ3-η2:η2(⊥)-nitrile complex 2, cationic μ3-η2:η2(⊥)-iminoacyl complex 6, and neutral μ3-η2:η2(⊥)-iminoacyl complex 3 revealed a clear trend of the activation of the C–N bond on a Ru3 plane. The thermolysis of 3b proceeded in a different manner to yield a μ3-methylidyne−μ3-η2(∥)-iminoacyl complex, (Cp*Ru)3(μ3-CH)(μ3-HNCH)(μ-H) (9), as a consequence of both C–N and C–C bond scission.