Structures and properties of octaethylporphinato(phenolate)iron(III) complexes with NH center dot center dot center dot O hydrogen bonds: modulation of Fe-O bond character by the hydrogen bond

摘要

Iron(III) porphinate complexes of phenolate that have NH...O hydrogen bonds on the coordinating oxygen, [Fe-III(OEP){O-2,6-(RCONH)(2)C6H3}] (R = CF3 (1), CH3 (3)) and [Fe-III(OEP)(O-2-RCONHC6H4)] (R = CF3 (2), CH3 (4)) (OEP = 2,3,7,8,12,13,17,18-octaethyl-21 H, 23H-porphinato), were synthesized and characterized as models of heme catalase. The presence of NH...O hydrogen bonds was established by their crystal structures and IR shifts of the amide NH band. The crystal structure of 1 shows an extremely elongated Fe-O bond, 1.926(3) Angstrom, compared to 1.887(2) Angstrom in 2 or 1.848(4) Angstrom in [Fe-III(OEP)(OPh)]. The NH...O hydrogen bond decreases an electron donation from oxygen to iron, resulting in a long Fe-O bond and a positive redox potential. (C) 2004 Elsevier B.V. All rights reserved.