title: Influence of Ligand Architecture in Tuning Reaction Bifurcation Pathways for Chlorite Oxidation by Non-Heme Iron Complexes.
abstract: Reaction bifurcation processes are often encountered in the oxidation of substrates by enzymes and generally lead to a mixture of products. One particular bifurcation process that is common in biology relates to electron transfer versus oxygen atom transfer by high-valent iron(IV)-oxo complexes, which nature uses for the oxidation of metabolites and drugs. In biomimicry and bioremediation, an important reaction relates to the detoxification of ClOx-in water, which can lead to a mixture of products through bifurcated reactions. Herein we report the first three water-soluble non-heme iron(II) complexes that can generate chlorine dioxide from chlorite at ambient temperature and physiological pH. These complexes are highly active oxygenation oxidants and convert ClO2-into either ClO2or ClO3¯ via high-valent iron(IV)-oxo intermediates. We characterize the short-lived iron(IV)-oxo species and establish rate constants for the bifurcation mechanism leading to ClO2and ClO3-products. We show that the ligand architecture of the metal center plays a dominant role by lowering the reduction potential of the metal center. Our experiments are supported by computational modeling, and a predictive valence bond model highlights the various factors relating to the substrate and oxidant that determine the bifurcation pathway and explains the origins of the product distributions. Our combined kinetic, spectroscopic, and computational studies reveal the key components necessary for the future development of efficient chlorite oxidation catalysts.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781 039, Assam, India.
authors.forename: Prasenjit
authors.initials: P
authors.lastname: Barman
authors.affiliation: Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester , 131 Princess Street, Manchester M1 7DN, United Kingdom.
authors.forename: Abayomi S
authors.initials: AS
authors.lastname: Faponle
authors.affiliation: Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781 039, Assam, India.
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Vardhaman
authors.affiliation: Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Davide
authors.initials: D
authors.lastname: Angelone
authors.affiliation: Anorganisch-Chemisches Institut and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University , Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
authors.forename: Anna-Maria
authors.initials: AM
authors.lastname: Löhr
authors.affiliation: Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Wesley R
authors.initials: WR
authors.lastname: Browne
authors.affiliation: Anorganisch-Chemisches Institut and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University , Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Comba
authors.affiliation: Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781 039, Assam, India.
authors.forename: Chivukula V
authors.initials: CV
authors.lastname: Sastri
authors.affiliation: Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester , 131 Princess Street, Manchester M1 7DN, United Kingdom.
authors.forename: Sam P
authors.initials: SP
authors.lastname: de Visser