The effect of N-ligands on the geometry, bonding, and electronic absorption properties of ruthenium carbonyl chains

摘要

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.