title: Photosystem II like water oxidation mechanism in a bioinspired tetranuclear manganese complex.
abstract: The synthesis of Mn-based catalysts to mimic the structural and catalytic properties of the oxygen-evolving complex in photosystem II is a long-standing goal for researchers. An interesting result in this field came with the synthesis of a Mn complex that enables water oxidation driven by the mild single-electron oxidant [Ru(bpy)3](3+). On the basis of hybrid density functional calculations, we herein propose a water oxidation mechanism for this bioinspired Mn catalyst, where the crucial O-O bond formation proceeds from the formal Mn4(IV,IV,IV,V) state by direct coupling of a Mn(IV)-bound terminal oxyl radical and a di-Mn bridging oxo group, a mechanism quite similar to the presently leading suggestion for the natural system. Of importance here is that the designed ligand is shown to be redox-active and can therefore store redox equivalents during the catalytic transitions, thereby alleviating the redox processes at the Mn centers.
authors.affiliation: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University , SE-10691 Stockholm, Sweden.
authors.forename: Rong-Zhen
authors.initials: RZ
authors.lastname: Liao
authors.forename: Markus D
authors.initials: MD
authors.lastname: Kärkäs
authors.forename: Bao-Lin
authors.initials: BL
authors.lastname: Lee
authors.forename: Björn
authors.initials: B
authors.lastname: Åkermark
authors.forename: Per E M
authors.initials: PE
authors.lastname: Siegbahn
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D008345:Manganese / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry; D011789:Quantum Theory; D017975:Ruthenium Compounds / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D016877:Oxidants; D045332:Photosystem II Protein Complex; D017975:Ruthenium Compounds; D014867:Water; D008345:Manganese; D015082:2,2'-Dipyridyl; D010100:Oxygen