Synthesis and Structure of a Triruthenium Complex Containing a Perpendicularly Coordinated <i>μ</i>₃-<i>η</i>²:<i>η</i>²(⊥)-Nitrile Ligand and Its Protonation To Yield a Perpendicularly Coordinated Iminoacyl Ligand

Treatment of the triruthenium pentahydrido complex {Cp*Ru(μ-H)}3(μ3-H)2 (1; Cp* = η5-C5Me5) with RCN (R = Ph, tBu) resulted in the exclusive formation of the μ3-η2:η2(⊥)-nitrile complex (Cp*Ru)3(μ3-η2:η2(⊥)-RCN)(μ3-H)(μ-H)2 (3a, R = Ph; 3b, R = tBu) with a coordination geometry of the nitrile ligand perpendicular to one of the Ru−Ru edges. Protonation of 3 quantitatively afforded the cationic μ3-iminoacyl complex [(Cp*Ru)3(μ3-η2:η2(⊥)-RCNH)(μ-H)2(μ3-H)](BF4) (4a, R = Ph; 4b, R = tBu), which clearly shows that the lone-pair electrons at the nitrogen atom do not participate in the bonding between the nitrile ligand of 3 and the metal centers.