Additive-Free Formic Acid Dehydrogenation Catalyzed by a Cobalt Complex

Abstract

The reversible storage of hydrogen through the intermediate formation of Formic Acid (FA) is a promising solution to its safe transport and distribution. However, the common necessity of using bases or additives in the catalytic dehydrogenation of FA is a limitation. In this context, two new cobalt complexes (<b>1</b> and <b>2</b>) were synthesized with a pincer PP(NH)P ligand containing a phosphoramine moiety. Their reaction with an excess FA yields a cobalt(I)-hydride complex (<b>3</b>). We report here the unprecedented catalytic activity of <b>3</b> in the dehydrogenation of FA, with a turnover frequency (TOF) of 4000 h<sup>-1</sup> and a turnover number (TON) of 454, without the need for bases or additives. A mechanistic study reveals that the ligand has a non-innocent behaviour due to intermolecular hydrogen bonding, which is influenced by the concentration of formic acid