The photoreaction between C 5H 5Fe(CO) 2Si(CH 3) 3 (I) and cyclohexyl isocyanide leads to the sequential replacement of both carbonyl groups by the isocyanide. Both the racemic monosubstituted product, C 5H 5Fe(CO)(C 6H 11NC)Si(CH 3) 3 (II) and the disubstituted product, C 5H 5Fe(C 6H 11NC) 2Si(CH 3) 3 (III) have been isolated and characterized. Photoreaction between the disubstituted product III and C 5H 5Fe(CO) 2Si(CH 3) 3 in a sealed tube gives the monosubstituted product, II. Thermal initiation of the above reactions failed. The disubstituted product III is stable under both the thermal and photochemical conditions used; thus, insertion of isocyanide into FeSi bond was observed not to occur.