Density functional, quadratic configuration interaction and electron propagator calculations have yielded structures, isomerization energies, and anion vertical electron detachment energies pertaining to Al 3 O nand Al 3 O n , where n ) 1, 2, or 3. These data suffice for an accurate assignment of recent anion photoelectron spectra. Peaks whose relative intensities vary with experimental conditions of ion preparation and transport are associated with isomers whose energies are close to those of the lowest singlet structures. Dyson orbitals associated with the lowest electron detachment energies are dominated by Al-centered functions with antibonding relationships to nearby O centers.

Density functional, quadratic configuration interaction, and electron propagator calculations have yielded structures, isomerization energies, and anion vertical electron detachment energies pertaining to AlO2, AlO2 -, Al3O5, and Al3O5 -. These data suffice for an accurate assignment of recent anion photoelectron spectra. Al3O5 - has a planar structure with three tricoordinate Al cations, three bridging oxides, and two terminal oxides. Dyson orbitals associated with the lowest electron detachment energies are dominated by p functions on terminal oxygens.

Structure and bonding in Al3O n and Al3O n - aluminum oxide clusters where n = 1−3 are studied with electronic structure calculations and are compared with some experimental results. Geometry optimizations with the B3LYP/6-311+G(2d,p) density functional method produced minima which were verified with frequency calculations. Several initial geometries and distinct spin multiplicities were considered for each case. The most stable anionic structures from density functional calculations were confirmed with additional geometry optimizations at the QCISD level. Equilibrium geometries, harmonic frequencies, and atomic charges are presented. These results, in combination with previous assignments of anion photoelectron spectra, provide a consistent explanation for changes in isomerization energies between anionic and neutral species.

A systematic density functional study of the structure and bonding in the alkali-metal pentadienyl complexes C 5 H 7 E (E ) Li-Cs) and their analogues derived from the 2,4-dimethylpentadienyl ligand is performed. The bonding in these structures has been analyzed in some detail with reference to molecular orbital analysis, and energy partition analysis, obtained by density functional calculations. An energy decomposition analysis indicates that the electrostatic interaction is the main factor to be considered in the stabilization of the gas-phase complexes we have studied. The stability of the U-shaped minimum energy structure decreases (the potential energy surface becomes more shallow) as the metal atom gets larger. We trace this behavior to a weakening of the metal-ligand binding due to the increasing diffuseness of the metal p orbitals on going down group 1. A significant pyramidalization at the terminal carbons in the coordinate U-shaped structure correlates with the strength of the metal-ligand binding. Initial results for the structural preferences of the complexes in solution for the lithium pentadienyl complex are examined in view of contrary experimental data. There still remains plenty of work to be done in modeling metal complexes in solution, and we suggest a way forward.