Reactions of ruthenium bipyridine catalyst precursors: Synthetic, structural, and theoretical studies on ruthenium mono(bipyridine) carbonyls in ethylene glycol solutions

Carbonyl-containing ruthenium mono(bipyridines) are effective catalysts or catalyst precursors in processes such as the water-gas shift reaction. Ethy lene glycol solutions provide versatile solvent systems for synthesizing th e mono(bipyridines) from [Ru(CO)(3)Cl-2](2) and 2,2'-bipyridine. These star ting compounds were used here in the preparation of three primary products, Ru(bpy)(CO)(2)Cl(C(O)OCH2CH2OH), Ru(bpy)(CO)(2)ClH, and [Ru(bpy)(CO)(2)Cl] (2), which were formed consecutively and isolated by adjusting the reaction conditions. Reactions were studied by analyzing the solid products and mon itoring the evolution of gases In each reaction step. Computational nonloca l density functional methods were applied to estimate the total reaction en ergies and to study isomerism of the compounds. Ethylene glycol solvent pla ys an active role in the synthesis reactions. It provides a reactive alkoxy group, -OCH2CH2OH, which is able to act as a nucleophile attacking the car bon of a Ru-CO group. The first product, Ru(bpy)(CO)(2)Cl(C(O)OCH2CH2OH), i s formed under mild conditions at room temperature. The alkoxy carbonyl com plex reacts further to Ru(bpy)(CO)(2)ClH and CO2 when heated. Formation of the hydride complex requires the presence of water. Ru(bpy)(CO)(2)ClH can b e further converted to dimeric [Ru(bpy)(CO)(2)Cl](2). Ru(bpy)(CO)(2)Cl-2 is a side product which is also obtained from [Ru(CO)(3)Cl-2](2) and 2,2'-bip yridine. Crystal data: Ru(bpy)(Co)(2)Cl(C(O)OCH2CH2OH). 1/4(HOCH2CH2OH) (1) , space group C2/c, cell constants a = 27.889(3) Angstrom, b = 10.270(2) An gstrom, c = 26.563(2) Angstrom, beta = 112.01(3)degrees, V = 7053.7(17) Ang strom(3), Z = 16; Ru(bpy)(CO)(2)ClH (2), P (1) over bar, a = 6.3871(10) Ang strom, b = 8.132(2) Angstrom, c = 12.693(3) Angstrom, alpha = 89.20(3)degre es, beta = 81.37(3)degrees, gamma = 81.20(3)degrees, V = 644.2(2) Angstrom( 3), Z = 2; [Ru(bpy)(CO)(3)Cl][Cl].(H5O2)(Cl) (3), Pbcn, a = 20.856(4) Angst rom, b = 13.523(3) Angstrom, c = 13.203(3) Angstrom, V = 3723.7(14) Angstro m(3), Z = 8.