Elucidation of a multiple S3 intermediates model for water oxidation in the oxygen evolving complex of photosystem II. Calcium-assisted concerted O[sbnd]O bond formation

Abstract

A multiple S3 intermediates model for water oxidation in the oxygen evolving complex (OEC) of photosystem II (PSII) is examined on the basis of key intermediates elucidated by UB3LYP/def2-TZVP and DLPNO-CCSD(T0) computations. The kinetic experimental results by this model are consistent with the main contribution of the Mn-Hydroxide configuration and partial contribution of Mn-Oxyl in the S3 state, for which the oxyl-radical character is largely reduced by the coordination of the Ca ion in OEC of PSII.