Mn/sup 2 +//Mn/sup 3 +/ and Mn/sup 3 +//Mn/sup 4 +/ mixed valence binuclear manganese complexes of biological interest

Journal Article · Wed Nov 11 00:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00257a057· OSTI ID:7160018

Dismukes, G C; Sheats, J E; Smegal, J A

Binuclear and multinuclear manganese containing enzymes which occur in biology are involved in functions such as hydrogen peroxide decomposition in bacteria and the oxidation of water to oxygen during photosynthesis, respectively. In the case of the water-oxidizing complex, the so-called S/sub 2/ oxidation state has been characterized by EPR spectroscopy to be a mixed valence manganese cluster. This can be produced in two forms. The native form, which is found in active O/sub 2/-evolving samples, is considered to be either tetranuclear or trinuclear in Mn, based upon interpretation of its broad 1500 G-wide 19-line multiline EPR signal and unusual temperature dependence. A partially decoupled form is found in inactivated samples having a narrow width (1345 G), with only 16 lines and a more Curie-like temperature dependence, all features which are found in typical Mn/sup 3 +//M/sup 4 +/ binuclear centers (16-line EPR, spin S = 1/2 ground state). For the native form both different oxidation states and different numbers for the manganese ions in the cluster have been proposed in order to account for the larger spectral width due to the hyperfine interaction with /sup 55/Mn. Both binuclear Mn/sup 2 +//Mn/sup 3 +/ and tetranuclear/sup 4/ 3Mn/sup 3 +//Mn/sup 4 +/ states have been considered. Notably lacking in this analysis has been EPR data for binuclear complexes in which both types of mixed valence oxidation states, Mn/sup 3 +//Mn/sup 4 +/ and Mn/sup 2 +//Mn/sup 3 +/, are compared within the same ligand system. The present report gives the first experimental evidence showing how /sup 55/Mn hyperfine data can easily distinguish between binuclear manganese complexes having these mixed valence oxidation states.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 7160018
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 109:23
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
14 SOLAR ENERGY
59 BASIC BIOLOGICAL SCIENCES
MANGANESE COMPLEXES
ELECTRON SPIN RESONANCE
PORPHYRINS
ENZYMES
EXPERIMENTAL DATA
HYPERFINE STRUCTURE
MANGANESE 55
VALENCE
CARBOXYLIC ACIDS
COMPLEXES
DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
MAGNETIC RESONANCE
MANGANESE ISOTOPES
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RESONANCE
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
140505 - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
550200 - Biochemistry