Biphenolate Iron (II) Complexes with Intramolecularly Coordinating Nitrogen Lewis Bases

Abstract

The synthesis and characterisation of a novel Fe(II) bisphenolate complex [Fe(OC{6}H{4}CH{2}NMe{2}-2){2}]{2} (1) from [Na(OC{6}H{4}CH{2}NMe{2}-2)] and anhydrous FeCl{2} is reported. The solid state structure has been elucidated by single crystal X-ray analysis and shows a dimeric structure with two bridging and two terminal phenolate ligands. Compound 1 reacts with pyridine to form the adduct [Fe(OC{6}H{4}CH{2}NMe{2}-2){2}(py){2}] (2). Similarly, 2 equiv. of [Na(OC{6}H{2}(CH{2}NMe{2}){2}-2, 6-Me-4)] were reacted with FeCl{2} and the thus in situ prepared '[Fe(OC{6}H{2}(CH{2}NMe{2}){2}-2,6-Me-4){2}]{n}' (3) was reacted with pyridine to form the adduct [Fe(OC{6}H{2}(CH{2}NMe{2}){2}-2,6-Me-4){2}(pyr){2}] (4). Compound 4 was characterised by single crystal X-ray analysis. Attempts to use these compounds as catalysts in the oxidation of cyclohexane with t-butylhydroperoxide (cat.:C{6}H{1}{2}:t-BuOOH=1:1000:100) resulted in the direct formation of brown coloured products, probably as a result of irreversible oxidation of 1, 2, 3 and 4, respectively. No cyclohexanol or cyclohexanone was formed.