Syntheses, structures and properties of a series of non-heme alkoxide-Fe(III) complexes of a benzimidazolyl-rich ligand as models for lipoxygenase

摘要

The treatment of Fe(ClO_4)_2·6H_2O or Fe(ClO_4)_3·9H_2O with a benzimidazolyl-rich ligand, N,N,N′,N′-tetrakis[(1-methyl-2- benzimidazolyl)methyl]-1,2-ethanediamine (medtb) in alcohol/MeCN gives a mononuclear ferrous complex, [Fe~(II)(medtb)](ClO_4) _2·CH_3CN·CH_3OH (1), and four non-heme alkoxide-iron(III) complexes, [Fe~(III)(OMe)(medtb)](ClO _4)_2·H_2O (2, alcohol = MeOH), [Fe ~(III)(OEt)(Hmedtb)](ClO_4)_3·CH _3CN (3, alcohol = EtOH), [Fe~(III)(OnPr)(Hmedtb)] (ClO_4)_3·~nPrOH·2CH_3CN (4, alcohol = n-PrOH), and [Fe~(III)(OnBu)(Hmedtb)](ClO _4)_3·3CH_3CN·H_2O (5, alcohol = n-BuOH), respectively. The alkoxide-iron(III) complexes all show 1) a Fe(III)-OR center (R = Me, 2; Et, 3; ~nPr, 4; ~nBu, 5) with the Fe-O bond distances in the range of 1.781-1.816 ?, and 2) a yellow color and an intense electronic transition around 370 nm. The alkoxide-iron(III) complexes can be reduced by organic compounds with a cis,cis-1,4-diene moiety via the hydrogen atom abstraction reaction.