title: Organometallic Iridium Complex Containing a Dianionic, Tridentate, Mixed Organic-Inorganic Ligand.
abstract: A pentamethylcyclopentadienyl-iridium complex containing a tricyclic, dianionic, tridentate, scorpionate (facial binding), mixed organic-inorganic ligand was synthesized and characterized by single-crystal X-ray crystallography, as well as polynuclear NMR, UV-vis, and IR spectroscopies. The central cycle of the tridentate ligand consists of a modified boroxine in which two of the boron centers are tetrahedral, anionic borates. The complex is stable to hydrolysis in aqueous solution for >9 weeks at 25 °C but reacts with a 50 mM solution of sodium periodate within 12 s to form a periodate-driven oxygen evolution catalyst that has a turnover frquency of >15 s(-1). However, the catalyst is almost completely deactivated within 5 min, achieving an average turnover number of ca. 2500 molecules of oxygen per atom of iridium. Nanoparticles were not observed on this time scale but did form within 4 h of catalyst activation under these experimental conditions. The parent complex was modeled using density functional theory, which accurately reflected the geometry of the complex and indicated significant interaction of iridium- and boracycle-centered orbitals.
authors.affiliation: Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Bloomfield
authors.affiliation: Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Matula
authors.affiliation: Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States.
authors.forename: Brandon Q
authors.initials: BQ
authors.lastname: Mercado
authors.affiliation: Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States.
authors.forename: Victor S
authors.initials: VS
authors.lastname: Batista
authors.affiliation: Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Crabtree