Direct Synthesis of Iron(0) N-Heterocyclic Carbene Complexes by Using Fe3(CO)12 and Their Application in Reduction of Carbonyl Groups

Iron Fe(NHC)(CO) 4 complexes were formed by direct reaction of Fe 3 (CO) 12 with equimolecular amounts of NHC imidazolium halide precursors; addition of base was not needed in this reaction. When excess (9:1 ratio) 1,3-dimesitylimidazolium chloride is reacted with the iron cluster Fe 3 (CO) 12, a mixture of Fe(IMes)(CO) 4 and Fe(IMes) 2 (CO) 3 is obtained. Single crystals of Fe(IMes)(CO) 4 and crystals resulting from the cocrystallization of Fe(IMes)(CO) 4 and Fe(IMes) 2 (CO) 3 have been studied by X-ray diffraction. These iron(0) complexes were found to catalyze the reduction of benzaldehydes.