title: Iron(III) complexes of bis (benzimidazol-2-yl) methyl) thiophene-2,5-dicarboxamide: synthesis, spectral and oxidation of o-phenylenediamine.
abstract: Iron(III) complexes of a potentially pentadentate ligand N(2), N(5)-bis ((1H-benzo [d] imidazol-2-yl) methyl) thiophene-2,5-dicarboxamide are synthesized with an exogenous anion X=Cl(-), NO(3)(-). Mössbauer and EPR spectroscopy indicates axially distorted complexes. These complexes were utilized for the oxidation of o-phenylenediamine to 2,3-diaminophenazine in presence of H(2)O(2). The initial rate of reaction is dependent on the concentration of o-phenylenediamine as well as the iron(III) complex. Rates of reaction were found to be at least five times higher for the Cl(-) bound complex. The effect of an added anion like acetate, azide and citrate is found to inhibit the rate of reaction. This suggests that one of the factors affecting the rate determining step is the binding of these anions on a vacant site at the iron(III) centre. The oxidation of o-phenylenediamine to 2,3-diaminophenazine is reminiscent of the functioning of horse radish peroxidase.
authors.affiliation: Department of Chemistry, University of Delhi, Delhi 110007, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Tyagi
authors.forename: Pavan
authors.initials: P
authors.lastname: Mathur
mesh_terms: D000838:Anions; D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D004553:Electric Conductivity; D055664:Electrochemical Techniques; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D005290:Ferric Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010655:Phenylenediamines / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D015204:Spectroscopy, Mossbauer; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D000838:Anions; D001562:Benzimidazoles; D005290:Ferric Compounds; D008024:Ligands; D010655:Phenylenediamines; D013876:Thiophenes; C034193:1,2-diaminobenzene; D006861:Hydrogen Peroxide; D007501:Iron