title: Experimental demonstration of radicaloid character in a Ru(V)=O intermediate in catalytic water oxidation.
abstract: Water oxidation is the key half reaction in artificial photosynthesis. An absence of detailed mechanistic insight impedes design of new catalysts that are more reactive and more robust. A proposed paradigm leading to enhanced reactivity is the existence of oxyl radical intermediates capable of rapid water activation, but there is a dearth of experimental validation. Here, we show the radicaloid nature of an intermediate reactive toward formation of the O-O bond by assessing the spin density on the oxyl group by Electron Paramagnetic Resonance (EPR). In the study, an (17)O-labeled form of a highly oxidized, short-lived intermediate in the catalytic cycle of the water oxidation catalyst cis,cis-[(2,2-bipyridine)2(H2O)Ru(III)ORu(III)(OH2)(bpy)2](4+) was investigated. It contains Ru centers in oxidation states [4,5], has at least one Ru(V) = O unit, and shows
authors: Department of Physics, Purdue University, West Lafayette, IN 47907, USA.
authors: Dooshaye
authors: D
authors: Moonshiram
authors: Igor
authors: I
authors: Alperovich
authors: Javier J
authors: JJ
authors: Concepcion
authors: Thomas J
authors: TJ
authors: Meyer
authors: Yulia
authors: Y
authors: Pushkar