Iron(III) complexes using NNS reduced Schiff bases and NNOS coordinating tetradentate ligands: Synthesis, structure and catecholase activity

The orange–red colored complexes of the type [Fe(LSB)Cl3], 1, have been synthesized in excellent yields by reacting FeCl3·6H2O with LSB in methanol. Here, LSB is (2-(ethylthio)-N-(pyridin-2-ylmethyl)ethanamine), (LSB1) and (2-(benzylthio)-N-(pyridin-2-ylmethyl)ethanamine) (LSB2). Similarly, FeCl3·6H2O reacted with 2-(((2-(ethylthio) ethyl) (pyridin-2-ylmethyl)amino)methyl)phenol (HL1), 2-(((2-(ethylthio)ethyl)(pyridin-2 ylmethyl)amino)methyl)-4-nitrophenol (HL2), 4-chloro-2-(((2-(ethylthio)ethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (HL3), 2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl) amino)methyl)phenol (HL4), 2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl)amino)methyl) -4-nitrophenol (HL5), and 4-chloro-2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl)amino) methyl)phenol (HL6) to give dichloro complexes of the type [Fe(L)Cl2], 2. The solid and solution structure of the complexes, as well as their properties, were probed using X-ray diffraction, spectroscopic and electrochemical methods. The Mössbauer spectral study at 80 K for complexes reveals the existence of (III) oxidation state and high-spin state of the metal center in the complex. Dioxygenase activity of the complexes has been studied and both 1 and 2 have been found to display the intradiol-cleaving pathway. However, no extradiol cleavage products have been isolated.