Both the announcement last year by the German Federal Government to eliminate the use of nuclear power generators by 2021 [1] and the recent shortage of electric power in California USA place renewed emphasis on development of socially acceptable energy sources such as solar [2] and fuel cells. [3] The latter cells rely on energy generated by the combination of H 2 (or hydrocarbons) with O 2 . Both of these molecules are expected to be produced by solar-based watersplitting catalysts (H 2 O 3 1 2O 2 H 2 ), hence, the efforts to understand Natures photosynthetic process of O 2 generation by water oxidation in plants, [4] and to functionally mimic the catalytic center, [5, 6] take on a pressing schedule. Key advances have occurred recently on both fronts with the first X-ray crystal structure at 3.8 resolution of the water-oxidizing complex (WOC) and its associated photochemical reaction center (photosystem II) from a cyanobacterium [7] and the first report of intramolecular O 2 photoproduction from the bridging oxygen atoms of a manganese ยฑ oxo cluster of cubane-type geometry, L 6 Mn 4 O 4 (1; L diphenylphosphinate; Ph 2 PO 2 ร ) Scheme 1. Reactions of L 6 Mn 4 O 4 cubane complexes 1 and 1': a) UV photochemical reaction in the gas phase and b) reductive dehydration reaction in solution. RXH organoammine, phenol, etc. Bridging phosphinates omitted for clarity.