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Title: Modeling the photosynthetic water oxidation center: Chloride/bromide incorporation and reversible redox processes in the complexes Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3} (X = Cl, Br) and (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]

Abstract

Synthetic procedures are described that allow conversion of [Mn{sub 4}O{sub 2}(OAc){sub 6}(py){sub 2}(dbm){sub 2}] (1, dbmH = dibenzoylmethane) to [Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3}] (X = Cl, 2; X = Br, 3). Treatment of 1 with Nbu{sup n}{sub 4}Cl in CH{sub 2}Cl{sub 2} or hot MeCn leads to 2 in 5-8% and 35-43% yields (based on dbm), respectively. A higher yield ({approximately}88%) is obtained by treating 1 with 4 equiv of Me{sub 3}SiCl in CH{sub 2}Cl{sub 2}. An analogous procedure with 4 equiv of Me{sub 3}SiBr in CH{sub 2}Br{sub 2} gives 3 in 55% yield. Treatment of [Mn{sub 3}O(OAc){sub 6}(py){sub 3}](ClO{sub 4}) in MeCN with Me{sub 3}SiCl followed by addition of H{sub 2}O and acetic acid results in crystallization of (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]{center_dot}2MeCN (4) in 75% yield (based on Mn). Cyclic volammetry at 100 mV/s and differential pulse voltammetry at 5 mV/s show that both 2 and 3 support a reversible oxidation and two reductions, the first of which is reversible. The reversible processes are at 1.09/1.06 and -0.25/-0.21 V vs ferrocene and show that the [Mn{sub 4}O{sub 3}X] core can exist at three oxidation levels spanning the 4Mn{sup III} to 2Mn{sup III}, 2Mn{sup IV} range. Themore » combined results from 2 and 3 show that the identity of X has minimal influence on the resultant structures, magnetic properties, {sup 1}H NMR and EPR spectral properties, or the redox behavior. Such observations are of interest with regard to the ability of Br{sup -} to successfully substitute for Cl{sub -} at the photosynthetic water oxidation center and thus maintain the activity of the tetranuclear Mn aggregate toward oxygen evolution.« less

Authors:
; ; ;  [1]
  1. Indiana Univ., Bloomington, IN (United States)
Publication Date:
OSTI Identifier:
513362
Resource Type:
Journal Article
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 35; Journal Issue: 26; Other Information: PBD: 18 Dec 1996
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; WATER; OXIDATION; PHOTOSYNTHESIS; REDUCTION; MANGANESE COMPLEXES

Citation Formats

Wang, Sheyi, Tsai, Hui-Lien, Libby, E, Folting, K, and Univ. of California, San Diego, CA. Modeling the photosynthetic water oxidation center: Chloride/bromide incorporation and reversible redox processes in the complexes Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3} (X = Cl, Br) and (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]. United States: N. p., 1996. Web. doi:10.1021/ic9601347.
Wang, Sheyi, Tsai, Hui-Lien, Libby, E, Folting, K, & Univ. of California, San Diego, CA. Modeling the photosynthetic water oxidation center: Chloride/bromide incorporation and reversible redox processes in the complexes Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3} (X = Cl, Br) and (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]. United States. doi:10.1021/ic9601347.
Wang, Sheyi, Tsai, Hui-Lien, Libby, E, Folting, K, and Univ. of California, San Diego, CA. Wed . "Modeling the photosynthetic water oxidation center: Chloride/bromide incorporation and reversible redox processes in the complexes Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3} (X = Cl, Br) and (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]". United States. doi:10.1021/ic9601347.
@article{osti_513362,
title = {Modeling the photosynthetic water oxidation center: Chloride/bromide incorporation and reversible redox processes in the complexes Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3} (X = Cl, Br) and (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]},
author = {Wang, Sheyi and Tsai, Hui-Lien and Libby, E and Folting, K and Univ. of California, San Diego, CA},
abstractNote = {Synthetic procedures are described that allow conversion of [Mn{sub 4}O{sub 2}(OAc){sub 6}(py){sub 2}(dbm){sub 2}] (1, dbmH = dibenzoylmethane) to [Mn{sub 4}O{sub 3}X(OAc){sub 3}(dbm){sub 3}] (X = Cl, 2; X = Br, 3). Treatment of 1 with Nbu{sup n}{sub 4}Cl in CH{sub 2}Cl{sub 2} or hot MeCn leads to 2 in 5-8% and 35-43% yields (based on dbm), respectively. A higher yield ({approximately}88%) is obtained by treating 1 with 4 equiv of Me{sub 3}SiCl in CH{sub 2}Cl{sub 2}. An analogous procedure with 4 equiv of Me{sub 3}SiBr in CH{sub 2}Br{sub 2} gives 3 in 55% yield. Treatment of [Mn{sub 3}O(OAc){sub 6}(py){sub 3}](ClO{sub 4}) in MeCN with Me{sub 3}SiCl followed by addition of H{sub 2}O and acetic acid results in crystallization of (pyH){sub 3}[Mn{sub 4}O{sub 3}Cl{sub 7}(OAc){sub 3}]{center_dot}2MeCN (4) in 75% yield (based on Mn). Cyclic volammetry at 100 mV/s and differential pulse voltammetry at 5 mV/s show that both 2 and 3 support a reversible oxidation and two reductions, the first of which is reversible. The reversible processes are at 1.09/1.06 and -0.25/-0.21 V vs ferrocene and show that the [Mn{sub 4}O{sub 3}X] core can exist at three oxidation levels spanning the 4Mn{sup III} to 2Mn{sup III}, 2Mn{sup IV} range. The combined results from 2 and 3 show that the identity of X has minimal influence on the resultant structures, magnetic properties, {sup 1}H NMR and EPR spectral properties, or the redox behavior. Such observations are of interest with regard to the ability of Br{sup -} to successfully substitute for Cl{sub -} at the photosynthetic water oxidation center and thus maintain the activity of the tetranuclear Mn aggregate toward oxygen evolution.},
doi = {10.1021/ic9601347},
journal = {Inorganic Chemistry},
number = 26,
volume = 35,
place = {United States},
year = {1996},
month = {12}
}