Modeling the photosynthetic water oxidation center: synthesis, structure, and magnetic properties of [Mn2(.mu.-O)2(.mu.-OAc)(H2O)2(bipy)2](ClO4)3.cntdot.H2O

Mn 2 (μ-O) 2 (μ-OAc)(H 2 O) 2 (bipy) 2 ] (ClO 4 ) 3 .H 2 O crystallizes in the monoclinic system, space group P2 1 /n (No.14) with Z=4 and a=13.619(1) A, b=16213(2) A, c=16.266(1) A, and β=113.08 (1) o . The structure was solved by direct methods and refined to conventional agreement indices R=0.021 and R w =0.024 with 5159 unique reflections for which I>3σ (I). The structure consists of binuclear [Mn IV 2 (μ-O) 2 (μ-OAc)(H 2 O) 2 (bipy) 2 ] 3+ cation separated by ClO 4 - anions and a molecule of water of crystallization