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Title: Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation

Abstract

The bridging ligand, 1,8-bis(2,2':6',2{double_prime}-terpyrid-4'-yl)anthracene (btpyan) was synthesized by the Miyaura-Suzuki cross coupling reaction of anthracenyl-1,8-diboronic acid and 4'-triflyl-2,2':6'-2{double_prime}-terpyridine in the presence of Pd(PPh{sub 3}){sub 4} (5 mol%) with 68% in yield. Three ruthenium-dioxolene dimers, [Ru{sub 2}(OH){sub 2}(dioxolene){sub 2}(btpyan)]{sup 0} (dioxolene = 3,6-di-tert-butyl-1,2-benzosemiquinone ([1]{sup 0}), 3,5-dichloro-1,2-benzosemiquinone ([2]{sup 0}) and 4-nitro-1,2-benzosemiquinone ([3]{sup 0})) were prepared by the reaction of [Ru{sub 2}Cl{sub 6}(btpyan)]{sup 0} with the corresponding catechol. The electronic structure of [1]{sup 0} is approximated by [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} (sq = semiquinonato). On the other hand, the electronic states of [2]{sup 0} and [3]{sup 0} are close to [Ru{sub 2}{sup III}(OH){sub 2} (cat){sub 2}(btpyan)]{sup 0} (cat = catecholato), indicating that a dioxolene having electron-withdrawing groups stabilizes [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0} rather than [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} as resonance isomers. No sign was found of deprotonation of the hydroxo groups of [1]{sup 0}, whereas [2]{sup 0} and [3]{sup 0} showed an acid-base equilibrium in treatments with t-BuOLi followed by HClO{sub 4}. Furthermore, controlled potential electrolysis of [1]{sup 0} deposited on an ITO (indium-tin oxide) electrode catalyzed the four-electron oxidation of H{sub 2}O to evolve O{sub 2} at potentials more positive than +1.6 V (vs. SCE) atmore » pH 4.0. On the other hand, the electrolysis of [2]{sup 0} and [3]{sup 0} deposited on ITO electrodes did not show catalytic activity for water oxidation under similar conditions. Such a difference in the reactivity among [1]{sup 0}, [2]{sup 0} and [3]{sup 0} is ascribed to the shift of the resonance equilibrium between [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} and [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0}.« less

Authors:
; ; ;
Publication Date:
Research Org.:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1020928
Report Number(s):
BNL-94963-2011-JA
R&D Project: CO-022; KC0301010; TRN: US201116%%953
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Dalton Transactions
Additional Journal Information:
Journal Volume: 40; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DIMERS; ELECTRODES; ELECTROLYSIS; ELECTRONIC STRUCTURE; ISOMERS; OXIDATION; PYROCATECHOL; RESONANCE; WATER

Citation Formats

Wada, T., Muckerman, J., Fujita, E., and Tanaka, K.. Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation. United States: N. p., 2010. Web.
Wada, T., Muckerman, J., Fujita, E., & Tanaka, K.. Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation. United States.
Wada, T., Muckerman, J., Fujita, E., and Tanaka, K.. Thu . "Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation". United States.
@article{osti_1020928,
title = {Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation},
author = {Wada, T. and Muckerman, J. and Fujita, E. and Tanaka, K.},
abstractNote = {The bridging ligand, 1,8-bis(2,2':6',2{double_prime}-terpyrid-4'-yl)anthracene (btpyan) was synthesized by the Miyaura-Suzuki cross coupling reaction of anthracenyl-1,8-diboronic acid and 4'-triflyl-2,2':6'-2{double_prime}-terpyridine in the presence of Pd(PPh{sub 3}){sub 4} (5 mol%) with 68% in yield. Three ruthenium-dioxolene dimers, [Ru{sub 2}(OH){sub 2}(dioxolene){sub 2}(btpyan)]{sup 0} (dioxolene = 3,6-di-tert-butyl-1,2-benzosemiquinone ([1]{sup 0}), 3,5-dichloro-1,2-benzosemiquinone ([2]{sup 0}) and 4-nitro-1,2-benzosemiquinone ([3]{sup 0})) were prepared by the reaction of [Ru{sub 2}Cl{sub 6}(btpyan)]{sup 0} with the corresponding catechol. The electronic structure of [1]{sup 0} is approximated by [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} (sq = semiquinonato). On the other hand, the electronic states of [2]{sup 0} and [3]{sup 0} are close to [Ru{sub 2}{sup III}(OH){sub 2} (cat){sub 2}(btpyan)]{sup 0} (cat = catecholato), indicating that a dioxolene having electron-withdrawing groups stabilizes [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0} rather than [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} as resonance isomers. No sign was found of deprotonation of the hydroxo groups of [1]{sup 0}, whereas [2]{sup 0} and [3]{sup 0} showed an acid-base equilibrium in treatments with t-BuOLi followed by HClO{sub 4}. Furthermore, controlled potential electrolysis of [1]{sup 0} deposited on an ITO (indium-tin oxide) electrode catalyzed the four-electron oxidation of H{sub 2}O to evolve O{sub 2} at potentials more positive than +1.6 V (vs. SCE) at pH 4.0. On the other hand, the electrolysis of [2]{sup 0} and [3]{sup 0} deposited on ITO electrodes did not show catalytic activity for water oxidation under similar conditions. Such a difference in the reactivity among [1]{sup 0}, [2]{sup 0} and [3]{sup 0} is ascribed to the shift of the resonance equilibrium between [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} and [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0}.},
doi = {},
journal = {Dalton Transactions},
number = 10,
volume = 40,
place = {United States},
year = {2010},
month = {12}
}