Synthesis and characterization of an iron(III) complex of glycine derivative of bis(phenol)amine ligand in relevance to catechol dioxygenase active site

A glycine derivative of bis(phenol)amine ligand (HLGly) was synthesized and characterized by 1H NMR and IR spectroscopies. The iron(III) complex (LGlyFe) of this ligand was synthesized and characterized by IR, UV–Vis, X-ray and magnetic susceptibility studies. X-ray analysis reveals that in LGlyFe the iron(III) center has a distorted trigonal bipyramidal coordination sphere and is surrounded by an amine nitrogen, a carboxylate and two phenolate oxygen atoms. The mentioned carboxylate group acts as μ-bridging ligand for iron centers of neighbor complexes. The variable-temperature magnetic susceptibility indicates that LGlyFe is the paramagnetic high spin iron(III) complex. It has been shown that electrochemical oxidation of this complex is ligand-centered due to the oxidation of phenolate to the phenoxyl radicals. The LGlyFe complex also undergoes an electrochemical metal-centered reduction of ferric to ferrous ion. The oxygenation of 3,5-di-tert-butyl-catechol, with LGlyFe in the presence of dioxygen was investigated.

Graphical abstractA glycine derivative of a bis(phenol)amine ligand (HLGly) was synthesized and characterized by 1H NMR and IR spectroscopies. The iron(III) complex (LGlyFe) of this ligand was synthesized and characterized by IR, UV–Vis, X-ray and magnetic susceptibility studies.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► An iron(III) complex of glycine derivative of bis(phenol)amine synthesized. ► The complex displayed paramagnetic properties. ► Electrochemical oxidation of complexes yielded the corresponding oxidized or reduced species.► The oxygenation of 3,5-di-tert-butyl-catechol, with this complex was investigated.