Characterization of the Fe V =O Complex in the Pathway of Water Oxidation.

Autor: Ezhov R; Department of Physics and Astronomy, Purdue University, 525 Northwestern avenue, West Lafayette, IN, 47906, USA., Ravari AK; Department of Physics and Astronomy, Purdue University, 525 Northwestern avenue, West Lafayette, IN, 47906, USA., Pushkar Y; Department of Physics and Astronomy, Purdue University, 525 Northwestern avenue, West Lafayette, IN, 47906, USA.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2020 Aug 03; Vol. 59 (32), pp. 13502-13505. Date of Electronic Publication: 2020 May 27.
DOI: 10.1002/anie.202003278
Abstrakt: Hypervalent Fe V =O species are implicated in a multitude of oxidative reactions of organic substrates, as well as in catalytic water oxidation, a reaction crucial for artificial photosynthesis. Spectroscopically characterized Fe V species are exceedingly rare and, so far, were produced by the oxidation of Fe complexes with peroxy acids or H 2 O 2 : reactions that entail breaking of the O-O bond to form a Fe V =O fragment. The key Fe V =O species proposed to initiate the O-O bond formation in water oxidation reactions remained undetected, presumably due to their high reactivity. Here, we achieved freeze quench trapping of six coordinated [Fe V =O,(OH)(Pytacn)] 2+ (Pytacn=1-(2'-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane) (2) generated during catalytic water oxidation. X-ray absorption spectroscopy (XAS) confirmed the Fe V oxidation state and the presence of a Fe V =O bond at ≈1.60 Å. Combined EPR and DFT methods indicate that 2 contains a S=3/2 Fe V center. 2 is the first spectroscopically characterized high spin oxo-Fe V complex and constitutes a paradigmatic example of the Fe V =O(OH) species proposed to be responsible for catalytic water oxidation reactions.
(© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
Externí odkaz: