C−C Bond Cleavage of Acetonitrile by a Carbonyl Iron Complex with a Silyl Ligand

Abstract

The photoreaction of a silyl iron complex Cp(CO)2Fe(SiMe3) (1) in acetonitrile in the presence of P(NMeCH2)2(OMe) (L) yielded Cp(CO)LFeMe (2), CpL2FeMe (3), and CpL2Fe(CN) (4), showing that carbon−carbon bond cleavage of acetonitrile was achieved. These C−C bond cleavage products were also obtained in the photoreaction of 1 with 1 equiv of MeCN in THF in the presence of L. The reaction with CD3CN showed that the methyl group on the iron in the products is derived from acetonitrile. The corresponding reaction of Cp(CO)2Fe(ER3) (ER3 = CH3, GeMe3, SnMe3) generated a CO/L exchange complex, Cp(CO)LFe(ER3), showing that a silyl ligand on the iron is indispensable for the C−C bond cleavage of acetonitrile. Theoretical studies on the C−C bond cleavage were performed using the hybrid DFT-B3LYP method. The direct C−C bond oxidative addition of acetonitrile to the 16e species Cp(CO)Fe(SiMe3) expected to readily form from 1 in the photoreaction conditions has a very high activation barrier of 52.7 kcal/mol, suggestin...