title: A synthetic model of the Mn₃Ca subsite of the oxygen-evolving complex in photosystem II.
abstract: Within photosynthetic organisms, the oxygen-evolving complex (OEC) of photosystem II generates dioxygen from water using a catalytic Mn(4)CaO(n) cluster (n varies with the mechanism and nature of the intermediate). We report here the rational synthesis of a [Mn(3)CaO(4)](6+) cubane that structurally models the trimanganese-calcium-cubane subsite of the OEC. Structural and electrochemical comparison between Mn(3)CaO(4) and a related Mn(4)O(4) cubane alongside characterization of an intermediate calcium-manganese multinuclear complex reveals potential roles of calcium in facilitating high oxidation states at manganese and in the assembly of the biological cluster.
authors.affiliation: Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard MC 127-72, Pasadena, CA 91125, USA.
authors.forename: Jacob S
authors.initials: JS
authors.lastname: Kanady
authors.forename: Emily Y
authors.initials: EY
authors.lastname: Tsui
authors.forename: Michael W
authors.initials: MW
authors.lastname: Day
authors.forename: Theodor
authors.initials: T
authors.lastname: Agapie
mesh_terms: D001952:Bridged-Ring Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D055664:Electrochemical Techniques; D008024:Ligands; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry*
chemical_list: D001952:Bridged-Ring Compounds; D002118:Calcium; D008024:Ligands; D008345:Manganese; D009942:Organometallic Compounds; D010087:Oxides; D010100:Oxygen; D045332:Photosystem II Protein Complex; C560340:cubane