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Many of the challenging chemical transformations indispensable for chemical industries can often
be carried out by nature under ambient conditions with remarkable reactivity and selectivity. For
example, methane monooxygenase is a class of nonheme diiron enzymes that catalyze the
challenging oxidation of methane into methanol with dioxygen as an oxidant. A high-valent
“diamond core” species Q (FeIV
2O2) is proposed to be the active intermediate responsible for
methane oxidation.1
In sharp contrast to biological systems, synthetic structural and functional
models of biological systems are limited in reactivity and selectivity in catalytic reactions.
Generation of active intermediates, their characterization with various spectroscopic techniques
and understanding their roles in catalysis are critical to the understanding of biological systems.
Syntheses and characterization of several high valent iron- and nickel-based active intermediates
(i.e., (L)FeV=O, (L)FeIV=O, (L)NiIII
-OH, and (L)NiIV
-OCl)2 will be discussed in this talk.
Resonance Raman and X-ray absorption spectroscopies and electrochemistry are utilized
extensively to understand the properties of those intermediates. Ultimately, this approach has
enabled us to relate these intermediates to their catalytic activities. I will also discuss potential
strategies to synthesize and characterize elusive M(III)-peroxynitrite (where M = Mn to Cu)
intermediates, powerful oxidizing and nitrating species proposed to be responsible for protein
damage that can cause a variety of cell injuries.
3 A better understanding of peroxynitrite/M(III)-
peroxynitrite will help us attenuate its toxic effects, which may provide insight to drug
development for inflammatory, cardiovascular, and neurodegenerative diseases.
1. (a) R. Banerjee, Y. Proshlyakov, J. D. Lipscomb, D. A. Proshlyakov, Nature 2015, 518, 431; (b) A. J. Jasniewski,
L. Que, Jr., Chem. Rev. 2018, 118, 2554.
2. (a) A. Draksharapu, D. Angelone, M. G. Quesne, S. K. Padamati, L. Gómez, M. Costas, W. R. Browne, S. P. de
Visser, Angew. Chemie., Int. Ed., 2015, 54, 4357; (b) A. Draksharapu, D. Angelone, M. G. Quesne, S. K. Padamati,
L. Gómez, M. Costas, W. R. Browne, S. P. de Visser, Angew. Chemie., Int. Ed., 2015, 54, 4357; (c) A. Draksharapu,
W. Rasheed, J. E. M. N. Klein, L. Que, Jr., Angew. Chemie., Int. Ed., 2017, 56, 9091; (d) A. Draksharapu, Z. Codolà,
L. Gómez, J. Lloret-Fillol, W. R. Browne, M. Costas, Inorg. Chem., 2015, 54, 10656; (e) R. Fan, J. Serrano-Plana, W.
N. Oloo, A. Draksharapu, E. Delgado-Pinar, A. Company, M. Borrell, J. Lloret-Fillol, E. García-España, Y. Guo, E.
L. Bominaar, L. Que Jr., M. Costas, E. Münck, J. Am. Chem. Soc. 2018, 140, 3916; (f) T. Corona, A. Draksharapu, S.
K. Padamati, I. Gamba, V. M. -Diaconescu, F. Acuña-Parés, W. R. Browne, A. Company, J. Am. Chem. Soc., 2016,
138, 12987.
3. (a) C. Szabó, H. Ischiropoulos, R. Radi, Nat. Rev. Drug. Discov., 2007, 6, 662. (b) J. Su, J. T. Groves, Inorg. Chem.,
2010, 49, 6317. |