A Novel Method for the Demetalation of Tricarbonyliron-Diene Complexes by a Photolytically Induced Ligand Exchange Reaction with Acetonitrile

The photochemical exchange of all three carbonyl ligands with acetonitrile converts tricarbonyliron-diene complexes into the very labile triacetonitrile-iron-diene complexes. These easily demetalate in high yields to the corresponding free ligands on injection of air at -30°C Eq. (1). The novel demetalation procedure is applied to the tricarbonyliron complexes of cyclopentadienones, cyclohexa-1,3-dienes, and buta-1,3-dienes.