Frapart, Y.-F., Boussac, A., Albach, R., Anxolabéhère-Mallart, E., Delroisse, M., Verlhac, J., Blondin, G., Girerd, J., Guilhem, J., Cesario, M., Rutherford, A.W. and Lexa, D. (1996) Chemical modeling of the oxygen-evolving center in plants. Synthesis, Structure and electronic and redox properties of a new mixed valence Mn-oxo cluster: [Mn2III,IVO2(bisimMe2en)2]3+ (bisimMe2en = N,N’-dimethylN,N’-bis(imidazol-4-ylmetyl)ethane-1,2-diamine). EPR detection of an imidazole radical induced by UV irradiation at

has been cited by the following article:

• TITLE: A B3LYP study on electronic structures of [(X)mMn(μ-oxo)2Mn(Y)n]q+ (X, Y = H2O, OH and O) as a Mn cluster model of OEC

  AUTHORS: Masashi Katsuda, Masaki Mitani, Yasunori Yoshioka

  KEYWORDS: Oxygen Evolving Complex; Manganese Binuclear; Oxidation Mechanism

  JOURNAL NAME: Journal of Biophysical Chemistry, Vol.3 No.2, May 29, 2012

  ABSTRACT: Electronic and molecular structures of [(X)mMn(μ-oxo)2Mn(Y)n]q+ (X, Y = H2O, OH and O), which are Mn cluster models at catalytic sites of OEC, were studied by broken-symmetry unrestricted B3LYP method. Two paths from the S0 to S3 states of Kok cycle were investigated. One is a path starting from [Mn(II) (μ-oxo)2Mn(III)] at the S0 state, and another is from [Mn(III) (μ-oxo)2Mn(III)] at the S0. Results found in this study are summarized as, 1) In [Mn(II), Mn(III)], it is not possible that H2O molecules coordinate to the Mn atoms with retaining the octahedral configuration. 2) The OHˉ anion selectively coordinates to Mn(IV) rather than Mn(III). 3) When the oxo atom directly bind to the Mn atom, the Mn atom must be a Mn(IV). From these results, the catalytic mechanism for four-electron oxidation of two H2O molecules in OEC is proposed. 1) The Mn4(II, III, IV, IV) at S0 is ruled out. 2) For Mn4(III, III, IV, IV) at S1, the Mn atom coordinated by OHˉ anion is a Mn(IV) not Mn(III). 3) Only Mn(III) ion which is coordinated by a H2O molecule at S0 plays crucial roles for the oxidation.