Aqueous phase carbon dioxide and bicarbonate hydrogenation catalyzed by cyclopentadienyl ruthenium complexes

Abstract

Abstract The water‐soluble ruthenium(II) complexes [Cp′RuX(PTA) 2 ]Y and [CpRuCl(PPh 3 )(mPTA)]OTf (Cp′ = Cp, Cp*, X = Cl and Y = nil; or X = MeCN and Y = PF 6 ; PTA = 1,3,5‐triaza‐7‐phosphaadamantane; mPTA = 1‐methyl‐1,3,5‐triaza‐7‐phosphaadamantane) were used as catalyst precursors for the hydrogenation of CO 2 and bicarbonate in aqueous solutions, in the absence of amines or other additives, under relatively mild conditions (100 bar H 2 , 30–80 °C), with moderate activities. Kinetic studies showed that the hydrogenation of HCO 3 − proceeds without an induction period, and that the rate strongly depends on the pH of the reaction medium. High‐pressure multinuclear NMR spectroscopy revealed that the ruthenium(II) chloride precursors are quantitatively converted into the corresponding hydrides under H 2 pressure. Copyright © 2007 John Wiley & Sons, Ltd.