Identification and spectroscopic characterization of nonheme iron(III) hypochlorite intermediates

Aquest mateix article està publicat a l'edició en alemany de la revista 'Angewandte Chemie' ISSN 0044-8249, EISSN 1521-3757), 2015, vol. 127, núm. 14, p. 4431–4435 http://dx.doi.org/10.1002/ange.201411995FeIII-hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme FeIII-hypohalite intermediates of possible relevance to iron halogenases. We show that FeIII-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT methods rationalize the pathways to the formation of the FeIII-OCl, and ultimately FeIV=O, species and provide indirect evidence for a short-lived FeII-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenasesFinancial support comes from the European Research Council (ERC-2011-StG-279549 to W.R.B.; ERC-2009-StG-239910 to M.C.), the Netherlands Fund for Technology and Science STW (11059, to W.R.B.) the Ministry of Education, Culture and Science (Gravity program 024.001.035 to A.D. and W.R.B.) and the Ubbo Emmius Fund of the University of Groningen (A.D.). The BBSRC is thanked for a studentship to M.G.Q. and COST action CM1003 “Biological oxidation reactions—mechanism and design of new catalyst” for funding of a short-term scientific mission to A.D. and D.A. The National (UK) Service of Computational Chemistry Software is acknowledged for providing CPU time (S.P.d.V.