Assembly of high-valent oxomanganese clusters in aqueous solution. Redox equilibrium of water-stable Mn sub 3 O sub 4 sup 4+ and Mn sub 2 O sub 2 sup 3+ complexes

Journal Article · Wed Sep 26 00:00:00 EDT 1990 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00176a027· OSTI ID:5494400

Sarneski, J E; Thorp, H H; Brudvig, G W; Crabtree, R H; Schulte, G K ^[1]

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1. Yale Univ., New Haven, CT (USA)

The aqueous chemistry of a binuclear mixed-valence cluster, ((bpy){sub 2}Mn(O){sub 2}Mn(bpy){sub 2})(ClO{sub 4}){sub 3} (1), has been investigated. The cluster exists in a pH-dependent equilibrium with a higher valent trinuclear species, (Mn{sub 3}O{sub 4}(bpy){sub 4}(OH{sub 2}){sub 2}){sup 4+} (2). The trinuclear cluster is favored at low pH, conditions that favor disproportionation of 1. Evaporation of a pH 1.9 solution of 1 leads to the precipitation of red crystals of 2 in the space group P{bar 1} with a = 14.902 (5) {angstrom}, b = 15.787 (5) {angstrom}, c = 12.676 (4) {angstrom}, {alpha} = 100.22 (2){degree}, {beta} = 93.45 (3){degree}, and {gamma} = 73.98 (3){degree}. The temperature-dependent magnetic susceptibility shows strong antiferromagnetic coupling. Electrochemistry and EPR show that the concentrations of 1 and 2 are governed by a pH-dependent equilibrium. The relevance of this quantitative equilibrium to the photoactivated assembly of the manganese tetramer in photosystem II is discussed.

• OSTI ID: 5494400
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 112:20; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MANGANESE COMPOUNDS
CRYSTAL STRUCTURE
MAGNETIC SUSCEPTIBILITY
AQUEOUS SOLUTIONS
CHEMICAL PREPARATION
PH VALUE
PHOTOSYNTHESIS
TEMPERATURE DEPENDENCE
CHEMICAL REACTIONS
DISPERSIONS
MAGNETIC PROPERTIES
MIXTURES
PHOTOCHEMICAL REACTIONS
PHYSICAL PROPERTIES
SOLUTIONS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
400500 - Photochemistry