Functional model for catecholase-like activity: Synthesis, structure, spectra, and catalytic activity of iron(III) complexes with substituted-salicylaldimine ligands

Four new mononuclear iron(III) complexes with the substituted-salicylaldimine ligands, [Fe(L1)(TCC)] (1), [Fe(L2)(TBC)] (2), [Fe(L3)(TBC)] (3) and [Fe(L4)(TCC)](CH3CN) (4) (HL1 = N′-(5-OH-salicylaldimine)-diethylenetriamine, HL2 = (N′-(5-Cl-salicylaldimine)-diethylenetriamine, HL3 N′-(5-Br-salicyl-aldimine)-dipropylenetriamine, HL4 = (N′-3,5-Br-salicylaldimine)-dipropylenetriamine, H2TCC = tetrachlorocatechol, and H2TBC = tetrabromocatechol), were prepared and characterized by XRD, EPR, and Mössbauer spectroscopy. The kinetic studied on the in situ prepared Fe(III) complexes [HL1 + FeCl3], [HL2 + FeCl3], [HL3 + FeCl3], and [HL4 + FeCl3] reaction with 3,5-DTBC (3,5-di-tert-butylcatechol) in the presence of air at pH 7.0 and 25 °C exhibit high catecholase activity.