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

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.