Carbon-Carbon Bond Formation in Multi-electron Reduction of Carbon Dioxide Catalyzed by [Ru(bpy)(trpy)(CO)]2+ (bpy = 2,2′-bipyridine; trpy = 2,2′:6′,2″-terpyridine)

Abstract

Controlled potential electrolysis of [Ru(bpy)(trpy)(CO)]2+ (bpy = 2,2′-bipyridine; trpy = 2,2′:6′,2″-terpyridine) at −1.70 V vs. Ag|Ag+ in CO2-saturated C2H5OH/H2O (8:2v/v) at −20 °C produced not only HCOOH and CO but also HC(O)H, CH3OH, H(O)CCOOH, and HOCH2COOH.

Molecular Catalysis of Electrochemical Reactions. Mechanistic Aspects

“…This is the case with Ru(bpy)(tpy)(CO) in 8-2 EtOH-H 2 O at -20 °C, where the product mixture contains CO, HCO 2 -, HCHO, CH 3 OH, H(O)CCO 2 and HOCH 2 CO 2 . [379][380][381][382][383] The possibility of forming 4-and 6-electron products hinges upon the stabilization of the CO adduct toward expulsion of CO, obtained by decreasing the temperature. A route is then opened to further electron transfers coupled with proton and/ or CO 2 transfers leading to the various products as depicted in Scheme 41.…”

New synthetic route to monocarbonyl polypyridyl complexes of ruthenium: their stereochemistry and reactivity

“…[5][6][7] As a third example, the complex [Ru(terpy)(bpy)(CO)] 2ϩ has been reported to chemically catalyse the electrochemical reduction of carbon dioxide to methanol. 8,9 The co-ordination compounds of ruthenium() containing polypyridyl ligands have drawn considerable interest due to their unique photophysical and redox characteristics. [10][11][12] The versatile series of complexes [Ru(ppp)(pp)X] nϩ was of particular interest to the authors in terms of the possibilities of tuning their photophysical and redox properties by appropriate choice of the monodentate ligand, in the same manner as observed for heteroleptic tris(bidentate) complexes of ruthenium.…”

Reactivity of CO2 Activated on Transition Metals and Sulfur Ligands

“…Reactions of nucleophiles with oxidatively activated M–CO are widely used to incorporate CO to organic substrates. For example, [Ru­(bpy) 2 (CO) 2 ] 2+ reacted with NaBH 4 to produce [Ru­(bpy) 2 (CO)­(CHO)] + and [Ru­(bpy) 2 (CO)­(CH 2 OH)] + . − Hydrolysis of the latter afforded MeOH. Therefore, reductive conversion of CO 2 to CO on metals, followed by attack of a nucleophile on the resultant M–CO scaffold prior to CO evolution, is a feasible pathway for preparing valuable molecules using CO 2 as a C1 building block.…”