Reactivity of naphthylimines toward Fe2(CO)9:: Observation of three different hydrogen migration pathways

The reaction of Fe-2(CO)(9) with imine ligands derived from alpha- or beta-naphthylcarbaldehydes leads to the formation of a series of iron carbonyl complexes. Most of them are produced by a C-H activation reaction in ortho position with respect to the exocyclic imine function. The reaction then proceeds via subsequent intramolecular hydrogen shift reactions and leads to several dinuclear compounds. Three different types of these hydrogen-transfer reactions were observed: a 1,3 hydrogen shift toward the former imine carbon atom, a 1,4 hydrogen shift toward the former imine nitrogen atom, or a 1,3 shift reaction toward one of the aromatic carbon atoms of the naphthalene system, which thus leaves the exocyclic imine function unreacted. In the reaction of beta-naphthyl derivatives the formation of trinuclear complexes is observed by the eta(4)-coordination of a third Fe(CO)3 group to the second ring of the naphthalene. Besides this, the first example of a structurally characterized (eta(4)-1-azadiene)Fe(CO)(3) complex with the C-C double bond formally being part of a cyclic aromatic system is obtained as a byproduct.