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 [(eta(5)-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).