title: Density functional theory calculations of selected Ru(II) two ring diimine complex dications.
abstract: Geometry optimization for a series of ten, two-ring diimine Ru(II) complexes was effected using the Gaussian 98 protocol at density functional theory (DFT) B3LYP level with basis sets 3-21G*and 3-21G**. HOMO-LUMO energy difference values compared favorably to the experimental data from electrochemistry [Delta E(1/2) = (E(1/2ox) - E(1/2red))] and the lowest energy absorption maxima, which for these complexes correspond to the metal-to-ligand charge transfer (MLCT) band. The HOMO and LUMO distributions from DFT support the idea that the lowest energy transitions are metal-to-ligand charge transfer and that the lowest energy LUMO for the mixed ligand complexes is located on 2,2'-bipyrazine (bpz), followed by 2,2'-bipyrimidine (bpm) and then 2,2'-bipyridine (bpy).
authors.affiliation: Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.
authors.forename: Stanislav R
authors.initials: SR
authors.lastname: Stoyanov
authors.forename: John M
authors.initials: JM
authors.lastname: Villegas
authors.forename: D P
authors.initials: DP
authors.lastname: Rillema