Which oxidation state is preferable at S_0 state in oxygen-evolving complex, Mn_4(II, III, IV, IV) or Mn_4(III, III, III, IV)? A B3LYP study

摘要

Based on the structure of 1.9 resolved OEC, which was published as PDBid = 3ARC, geometries and electronic structures of the CaMn_4O_5 core and surrounding water molecules at the S 0 state are examined by the hybrid B3LYP and broken-symmetry methods. Two doublet states 1 and 2 with energy difference of 15.2 kcal/mol were obtained. 1 is lower than 2. The oxidation states of four manganese atoms of 1 are Mn 4[III, III, IV, III], while those of 2 are Mn_4[III, IV, IV, II]. It is concluded that the oxidation states of Mn_4(II, III, IV, IV) is ruled out at the S_0 state.