In this contribution we describe the synthesis, thorough identification, and unique catalytic properties of small gold nanoparticles ligated by secondary phosphine oxides. The gold nanoparticles containing on average 50 gold atoms and 30 SPO ligands are easy to make in a reproducible manner. The AuNP@SPO nanoparticles have been fully identified. They are very selective catalysts for the hydrogenation of aldehydes in the presence of any functional group, except thiols and terminal alkynes which partly inhibit the reaction; not even acroleine shows a sign of alkene hydrogenation. The ligands play a crucial triple role, as stabilizers for the nanoparticles, as modifying ligands, and as functional ligands supplying the oxygen function that participates in the heterolytic cleavage of dihydrogen. We have proven that the secondary phosphine is present as the R2P=O anionic species, similar to thiolates in AuNPs, coordinating to gold with the phosphorus atom and perhaps also by the oxygen atom. We suggest that the oxygen atom of the secondary phosphine oxide plays a role similar to the oxygen atoms of oxide supports in the heterolytic cleavage and hydrogenation.

Metal nanoparticles ligated by secondary phosphine oxides

248th National Meeting (2014)

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