Towards an easy carbon dioxide reduction in aqueous solution

The homogeneous hydrogenation of carbon dioxide into formate anion has been investigated in aqueous solution, using water soluble ruthenium(II)-phosph ine (meta-monosulphonated triphenylphosphine, TPPMS; and 1,3,5-triaza-7-pho sphaadamantane, PTA) complexes as catalysts. These reactions take place in amine free medium under mild conditions, bicarbonate anion is more active t han carbon dioxide in the reduction. The initial turnover frequency of the reduction increases with increasing H-2 pressure, as it was observed in sit u by C-13 and H-1 NMR spectroscopy. High pressure FT-IR were used to find e vidence for the formation of the catalytically active ruthenium hydride spe cies.