A Robust Synthesis of CoP and NiP Nanocatalysts from Hexaethylaminophosphine and Phosphine-Enhanced Phenylacetylene Hydrogenation.

Metal-rich phases of general formula MP have demonstrated interesting catalytic activity, e.g., for hydrogen evolution reaction and for hydrogenations in colloidal suspension. The production of well-crystallized nanoparticles of the MP phase from commercial precursors on a large enough scale is not trivial as the existing routes generally require fairly high reaction temperatures and a large excess of the phosphorus source. Here, we selected a commercial aminophosphine, P(NEt), as the phosphorus precursor (3 equiv or less) to develop a robust synthesis from CoCl (respectively NiCl) that provided crystalline CoP (respectively NiP) nanoparticles with high yields on a 9 mmol scale. Moreover, modification of the MP nanoparticles via the addition of a molecular Lewis base is a promising route to trigger catalytic activity of the colloidal suspension at a lower temperature. For the hydrogenation of phenylacetylene catalyzed by CoP and NiP nanoparticles, we showed that catalytic amounts of adequate phosphines, such as PBu and also, in some instances, oleylamine, triggered a full conversion at lower temperatures than with the nanoparticles alone. We delineated the most efficient phosphines in the case of a NiP catalyst, using a stereoelectronic map of 13 phosphines.