Abstract The reactions of [Fe2Cp2(CO)4] with a series isocyanides, CNR, were conducted in acetonitrile and afforded, after thermal treatment, the mono-isocyanide derivatives [Fe2Cp2(CO)3(CNR)] [R = 1H-indol-5-yl, 1; CH2P(O)(OEt)2, 2; Cy = C6H11, 3; 4-C6H4OMe, 4; Xyl = 2,6-C6H3Me2, 5; Me, 6; 2-naphthyl, 7; Bn = CH2Ph, 8]. In order to avoid multiple substitution, diiron reactant was used molar ex...