Synthesis, characterization and derivatization of hydroxyl-functionalized iron(II) bis(NHC) complexes

The syntheses of a novel hydroxyl-functionalized tetradentate NHC/pyridine hybrid ligand and the corresponding Ag(i) and Fe(ii) complexes are presented. Spectroscopic and X-ray diffraction techniques are used for structural investigations and cyclic voltammetry measurements reveal interesting electronic properties. Transmetalation of the trinuclear Ag(i) complex (C1) yields a mononuclear and a dinuclear iron(ii) bis(NHC) complex (C2 and C3), which can be separated by stepwise precipitation. The former is isostructural to iron(ii) bis(NHC) complex A, which is a versatile oxidation catalyst. Furthermore, suitable conditions for esterification reactions of the ligand precursor and iron(ii) bis(NHC) complex (C2) have been established, demonstrating the utility of the hydroxyl functionality for immobilization and derivatization purposes.