Synthesis of stable phosphomide ligands and their use in Ru-catalyzed hydrogenations of bicarbonate and related substrates

Abstract

New benzoyl- and naphthoyl-substituted phosphines have been synthesized, which are stable to air and moisture. Testing these so-called phosphomide ligands in the presence of different ruthenium precursors, the hydrogenation of sodium bicarbonate (NaHCO(3)) to sodium formate (NaHCO(2)) proceeded with good catalyst turnover numbers in the range of 1300-1600 at 80°C and a total pressure of hydrogen of 60 bar in the absence of amines or other additives. Similarly, catalytic hydrogenations of carbon dioxide, cinnam-, and benzaldehyde were possible with these new ruthenium complexes. As an intermediate of the catalytic cycle the defined ruthenium complex [(η(6)-C(6)H(6))-RuCl(2)(Cy(2)P(1-naphthoyl)] (Cy=cyclohexyl) was prepared and characterized by X-ray crystallography.