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Title: Polarized X-ray Absorption Spectroscopy of Single-crystal Mn(V)Complexes Relevant to the Oxygen-Evolving Complex of Photosystem II

Abstract

High-valent Mn=O species have been suggested to have acatalytically important role in the water splitting reaction which occursin the Photosystem II membrane protein. In this study, five- andsix-coordinate mononuclear Mn(V) compounds were investigated by polarizedX-ray absorption spectroscopy in order to understand the electronicstructure and spectroscopic characteristics of high-valent Mn species.Single crystals of the Mn(V)-nitrido and Mn(V)-oxo compounds were alignedalong selected molecular vectors with respect to the X-ray polarizationvector using X-ray diffraction. The local electronic structure of themetal site was then studied by measuring the polarization dependence ofX-ray Absorption Near Edge Spectroscopy (XANES) pre-edge spectra (1s to3d transition) and comparing with the results of density functionaltheory (DFT) calculations. The Mn(V)-nitrido compound, in which themanganese is coordinated in a tetragonally distorted octahedralenvironment, showed a single dominant pre-edge peak along the Mn?N axisthat can be assigned to a strong 3dz2 - 4pz mixing mechanism. In thesquare pyramidal Mn(V)-oxo system, on the other hand, an additional peakwas observed at 1eV below the main pre-edge peak. This component, whichdoes not show noticeable dichroism, was interpreted as a 1s to 3dxz, yztransition with 4px,y mixing, due to the displacement of the Mn atom outof the equatorial plane. The XANES results have been correlated to DFTcalculations, andmore » the spectra have been simulated using a TD (timedependent)-DFT approach. The relevance of these results to understandingthe mechanism of the photosynthetic water oxidation isdiscussed.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science; National Institutes ofHealth
OSTI Identifier:
929666
Report Number(s):
LBNL-62495
Journal ID: ISSN 0002-7863; JACSAT; R&D Project: 864N1F; BnR: 400412000; TRN: US200812%%739
DOE Contract Number:  
DE-AC02-05CH11231; NIHGM 55302
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 129; Journal Issue: 43; Related Information: Journal Publication Date: 2007; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
English
Subject:
36; ABSORPTION; ABSORPTION SPECTROSCOPY; ATOMS; DICHROISM; ELECTRONIC STRUCTURE; FUNCTIONALS; MANGANESE; MEMBRANE PROTEINS; MONOCRYSTALS; OXIDATION; POLARIZATION; SPECTRA; SPECTROSCOPY; VECTORS; WATER; X-RAY DIFFRACTION; Photosynthesis oxygen-evolving comples X-rayspectroscopy

Citation Formats

Yano, Junko, Robblee, John, Pushkar, Yulia, Marcus, Matthew A, Bendix, Jesper, Workman, Jose M, Collins, Terrence J, Solomon, EdwardI, DeBeer George, Serena, and Yachandra, Vittal K. Polarized X-ray Absorption Spectroscopy of Single-crystal Mn(V)Complexes Relevant to the Oxygen-Evolving Complex of Photosystem II. United States: N. p., 2007. Web. doi:10.1021/ja071286b.
Yano, Junko, Robblee, John, Pushkar, Yulia, Marcus, Matthew A, Bendix, Jesper, Workman, Jose M, Collins, Terrence J, Solomon, EdwardI, DeBeer George, Serena, & Yachandra, Vittal K. Polarized X-ray Absorption Spectroscopy of Single-crystal Mn(V)Complexes Relevant to the Oxygen-Evolving Complex of Photosystem II. United States. https://doi.org/10.1021/ja071286b
Yano, Junko, Robblee, John, Pushkar, Yulia, Marcus, Matthew A, Bendix, Jesper, Workman, Jose M, Collins, Terrence J, Solomon, EdwardI, DeBeer George, Serena, and Yachandra, Vittal K. Wed . "Polarized X-ray Absorption Spectroscopy of Single-crystal Mn(V)Complexes Relevant to the Oxygen-Evolving Complex of Photosystem II". United States. https://doi.org/10.1021/ja071286b.
@article{osti_929666,
title = {Polarized X-ray Absorption Spectroscopy of Single-crystal Mn(V)Complexes Relevant to the Oxygen-Evolving Complex of Photosystem II},
author = {Yano, Junko and Robblee, John and Pushkar, Yulia and Marcus, Matthew A and Bendix, Jesper and Workman, Jose M and Collins, Terrence J and Solomon, EdwardI and DeBeer George, Serena and Yachandra, Vittal K},
abstractNote = {High-valent Mn=O species have been suggested to have acatalytically important role in the water splitting reaction which occursin the Photosystem II membrane protein. In this study, five- andsix-coordinate mononuclear Mn(V) compounds were investigated by polarizedX-ray absorption spectroscopy in order to understand the electronicstructure and spectroscopic characteristics of high-valent Mn species.Single crystals of the Mn(V)-nitrido and Mn(V)-oxo compounds were alignedalong selected molecular vectors with respect to the X-ray polarizationvector using X-ray diffraction. The local electronic structure of themetal site was then studied by measuring the polarization dependence ofX-ray Absorption Near Edge Spectroscopy (XANES) pre-edge spectra (1s to3d transition) and comparing with the results of density functionaltheory (DFT) calculations. The Mn(V)-nitrido compound, in which themanganese is coordinated in a tetragonally distorted octahedralenvironment, showed a single dominant pre-edge peak along the Mn?N axisthat can be assigned to a strong 3dz2 - 4pz mixing mechanism. In thesquare pyramidal Mn(V)-oxo system, on the other hand, an additional peakwas observed at 1eV below the main pre-edge peak. This component, whichdoes not show noticeable dichroism, was interpreted as a 1s to 3dxz, yztransition with 4px,y mixing, due to the displacement of the Mn atom outof the equatorial plane. The XANES results have been correlated to DFTcalculations, and the spectra have been simulated using a TD (timedependent)-DFT approach. The relevance of these results to understandingthe mechanism of the photosynthetic water oxidation isdiscussed.},
doi = {10.1021/ja071286b},
url = {https://www.osti.gov/biblio/929666}, journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 43,
volume = 129,
place = {United States},
year = {2007},
month = {2}
}