title: The effect of N-ligands on the geometry, bonding, and electronic absorption properties of ruthenium carbonyl chains.
abstract: The stability and structural properties of linear chain compounds [Ru(L)(CO)(1-2)](n) (L = substituted or unsubstituted 2,2'-biimidazole, 2,2'-bipyridine, 1,10-phenantroline, or 2,2':6',2''-terpyridine) were investigated by computational DFT methods. The favored torsional orientation of the neighboring units in the chain was studied using dinuclear (n = 2) models. Models up to 8 [Ru(L)(CO)(1-2)] units were used to analyze Ru-Ru interactions by Mayer bond order and charge density analysis. Compared to the related polymeric compound [Ru(CO)(4)](n), the presence of chelating nitrogen ligands led to slightly weaker Ru-Ru bonds. Electronic structures and corresponding excitations were investigated by TD-DFT methods. The studied nitrogen ligands, especially biimidazole compared to polypyridines, were found to produce differences in the absorption characteristics of the chains. Moreover, as the chain length was increased, a red-shift in excitations was observed. The results show that even with rather subtle structural changes in the surrounding ligands, we can produce significant effect on the properties of the materials.
authors.affiliation: Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Niskanen
authors.forename: Pipsa
authors.initials: P
authors.lastname: Hirva
authors.forename: Matti
authors.initials: M
authors.lastname: Haukka