Photosynthetic water oxidation center: spin frustration in distorted cubane MnIVMnIII3 model complexes

The photosystem II water oxidation center (WOC) (S{sub 2} state) was modeled using four Mn{sup IV}Mn{sup III} complexes. Chemical preparation of the complexes and the structural characterization of them is discussed discussed. Results of X-ray crystallography, IR absorption, NMR, and EPR studies for these complexes are reported and conclusions concerning the electronic structure are presented. 57 refs., 15 figs., 7 tabs.