To illustrate the basic structure and the catalytic mechanism of catalase (CAT), three Fe^Ⅱ complexes were systhesized through the reaction of N ,N ,N - tris (2 - benzimidazolmethyl)amine (NTB), ,N,N' ,N'-tetrakis (2'-benzimidazolylmethyl)']-orhto-diamine-trans-cyclohexane (CTB) with Fe^Ⅱ complexes in alcohol. They were [Fe (NTB)Cl2]Cl·3H2O (Ⅰ), [Fe (CTB) (OAc)Cl]Cl·2H2O ( 1 )and [Fe (CTB)](ClO4)3·3CH3OH·2H2O ( Ⅲ ). All complexes have been characterized by elemental analyses, conductivity measurements, NMR,...