Synthesis, structure, and properties of a binuclear Fe(III) complex with N-(1-propanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl)amine

Mannich reaction of 2-Amino propanol, 2-tert-butyl-4-methylphenol, and formaldehyde in the ratio of 1:2:2 provides a new compound, N-(1-propanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl)amine (H3L), which has been characterized by X-ray crystallography and elemental analysis. In the presence of Et3N, the reaction of H3L and FeCl3·6H2O gives a dinuclear Fe(III) complex [Fe2L2] 1, which has been characterized by X-ray crystallography, magnetic measurement, and cyclic voltammetry. The value of μeff at room temperature (5.97 μB) is much less than the expected spin-only value (8.37 μB) of two high spin (hs) Fe3+ (S = 5/2) ions [μ = g[∑ZS(S + 1)]1/2], indicating there are strong coupling interactions between Fe3+ ions. The magnetic behavior of 1 denotes the occurrence of intramolecular antiferromagnetic interactions (J = −13.35 cm−1). CV of 1 reveals two reversible waves at 0.433 and 1.227 V versus AgCl/Ag, which can be ascribed to the successive redox coupling of FeIIFeII/FeIIIFeII and FeIIIFeII/FeIIIFeIII, respectively.