Reactivity of the Iron Complexes with the Macrocyclic Ligand 5,5,7,12,12,14‐Hexamethyl‐1,4,8,11‐Tetraazacyclotetradecane (tet) Toward Dioxygen

The reactions of the iron complexes [(tet a)Fe II (OTf) 2 ] and [(tet b)Fe II ](OTf) 2 (tet = 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane) with dioxygen were investigated. While [(tet b)Fe II ](OTf) 2 undergoes slow oxidation to an iron(III) compound without detectable intermediates, [(tet a)Fe II (OTf) 2 ] initially formed a superoxido complex which subsequently converted into the corresponding iron–oxido complex. Although attempts to structurally characterize [(tet a)Fe IV (O)(OTf)](OTf) were unsuccessful, the complex could be characterized spectroscopically. In addition, during attempts to crystallize [(tet b)Fe II ](OTf) 2 , an aldol reaction of the solvent acetone was observed, yielding diacetone alcohol (DAA), which was found to coordinate to the iron complex.