title: A well-defined terminal vanadium(III) oxo complex.
abstract: The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [V(II)(NCCH3)(PY5Me2)](2+) (1) to either dioxygen or selected O-atom-transfer reagents yields [V(IV)(O)(PY5Me2)](2+) (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [V(III)(O)(PY5Me2)](+) (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720-1460, United States.
authors.forename: Amanda E
authors.initials: AE
authors.lastname: King
authors.forename: Michael
authors.initials: M
authors.lastname: Nippe
authors.forename: Mihail
authors.initials: M
authors.lastname: Atanasov
authors.forename: Teera
authors.initials: T
authors.lastname: Chantarojsiri
authors.forename: Curtis A
authors.initials: CA
authors.lastname: Wray
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.forename: Frank
authors.initials: F
authors.lastname: Neese
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Long
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Chang
mesh_terms: D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D011789:Quantum Theory; D014639:Vanadium / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D014639:Vanadium; D010100:Oxygen