Iron‐Complex‐Catalyzed C?C Bond Cleavage of Organonitriles: Catalytic Metathesis Reaction between H?Si and R?CN Bonds to Afford R?H and Si?CN Bonds

The first example of the catalytic C? CN bond cleavage of acetonitrile as well as Si? CN bond formation have been achieved in the photoreaction of MeCN with Et₃SiH promoted by Cp(CO)₂FeMe]. This catalytic system is applicable to other organonitriles. Several iron complexes (η⁵‐C₅R₅)(CO)₂FeR′] (R₅=H₅, H₄Me, Me₅, H₄SiMe₃, H₄I, H₄P(O)(OMe)₂; R′=SiMe₃, CH₂Ph, Me, Cl, I) were examined as catalyst, and Cp(CO)₂FeMe] was found to be the best precursor. A catalytic reaction cycle was proposed, which involves oxidative addition of Et₃SiH to Cp(CO)FeMe], reductive elimination of CH₄ from Cp(CO)FeMe(H)(SiEt₃)], coordination of RCN to Cp(CO)Fe(SiEt₃)], silyl migration from Fe to N in the coordinated RCN, and dissociation of Et₃SiNC from Fe. The reaction with MeCN of Cp(CO)Fe(py)(SiEt₃)], which was newly prepared and determined by X‐ray analysis, and the reaction of Et₃SiH with MeCN in the presence of a catalytic amount of Cp(CO)Fe(py)(SiEt₃)] showed that the 16‐electron species Cp(CO)Fe(SiEt₃)] is the active species in the catalytic cycle (TON up to 251).