Synthesis of Oligo(Triarylphosphine Sulfide)s for Stabilizing Pd Nanoparticles and Modulating Selective Semihydrogenation of Terminal Aryl Alkynes

Pd nanoparticles, stabilized by a series of oligo(triarylphosphine sulfide)s, were prepared and evaluated as catalysts for the semihydrogenation of phenylacetylene. Stabilizing agents with a high number of coordination sites and a combination of p-phenylene and m-phenylene linkers yielded small-sized Pd nanoparticles, demonstrating high catalytic performances.

Abstract

In the development of high-performance metal nanoparticle (NP) catalysts, the exploration of new classes of multidentate organic stabilizers is crucial. Herein, we report the synthesis of a series of structurally diverse oligo(triarylphosphine sulfide)s via the Pd-catalyzed P–C cross-coupling reactions of hydroxymethylphosphine sulfide derivatives with aryl halides. The oligomers were employed as stabilizing agents for Pd NP catalysts. These catalysts were characterized by TEM, EDS, and ICP-MS analyses to determine the average Pd particle size and the constituent elements on the catalyst. We evaluated their catalytic activity in the semihydrogenation of phenylacetylene to styrene in EtOH at 70 °C for 3 h under atmospheric pressure of H₂ with a catalyst loading of 0.5 mol% Pd. It was revealed that Pd NPs stabilized with oligo(triarylphosphine sulfide)s, featuring a high number of coordination sites and a combination of p-phenylene and m-phenylene linkers, exhibited high selectivity for styrene and low Pd leaching.

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