Iron(III) Complexes Based on N-Benzylidene-2-Hydroxy-3,5-Di-tert-Butylaniline

Abstract

Five-coordinate iron(III) complexes, (ImPh)2FeX (X = Cl (I), Br (II), I (III), N3 (IV)) containing two bidentate Schiff bases (N-benzylidene-2-hydroxy-3,5-di-tert-butylaniline (ImPh)H) and a halogen atom/azide group in the coordination sphere were synthesized and characterized in detail. According to the magnetic susceptibility measurements for polycrystalline samples of I–IV and Mossbauer spectroscopy data in the 2–300 K range, the complexes contain a high-spin metal ion (HS Fe3+, d5, SFe = 5/2). Compounds I–IV are stable in the crystalline state in the absence of oxygen or air moisture; however, in solution, they undergo symmetrization, resulting in the formation of the tris-ligand complex (ImPh)3Fe (V), which was also synthesized by the reaction (ImPh)H and FeCl3 (3 : 1). Unlike five-coordinate complexes I–IV, six-coordinate complex V contains low-spin iron(III) ion (LS Fe3+, d5, SFe = 1/2). The molecular structure of I was determined by X-ray diffraction (CIF file CCDC no. 1996527).