Gas-Phase Vanadium Oxide Anions: Structure and Detachment Energies from Density Functional Calculations

Mononuclear and binuclear vanadium oxide anions, VO y - ( y = 1−4) and V 2 O y - ( y = 4, 6, and 7), as well as the polynuclear V 3 O 8 -, V 4 O 10 -, and V 4 O 11 - anions are examined using density functional methods. Comparison is made with the corresponding neutral systems, and the vertical detachment energies of the anions and the adiabatic electron affinities of the neutrals are calculated. A triple-ζ valence plus polarization basis set is adopted and the B3LYP and BP86 functionals are employed. The two functionals yield very similar structures for all systems studied. The electron detachment energies of the anions display two important trends. First, they increase strongly with increasing metal oxidation state. Second, the electron detachment energies increase with a higher delocalization of the unpaired electron of the anion. The electron detachment energies of peroxo complexes are not higher than those of analogous complexes without an O 2 ligand. Energies for oxygen uptake decrease with increasing oxygen-to-vanadium ratio. They are particularly low when a peroxo group is formed. Formation of larger species from smaller ones is energetically favorable. The V 3 O 8 - ion appears to be particularly stable.