Enabling Semihydrogenation of Alkynes to Alkenes by Using a Calcium Palladium Complex Hydride

Qing Guo; Ruting Chen; Jianping Guo; Chao Qin; Zhitao Xiong; Hanxue Yan; Wenbo Gao; Qijun Pei; Anan Wu; Ping Chen

doi:10.1021/jacs.1c09489

Enabling Semihydrogenation of Alkynes to Alkenes by Using a Calcium Palladium Complex Hydride

J Am Chem Soc. 2021 Dec 15;143(49):20891-20897. doi: 10.1021/jacs.1c09489. Epub 2021 Dec 2.

Authors

Qing Guo^{1

2}, Ruting Chen³, Jianping Guo^{1

2}, Chao Qin¹, Zhitao Xiong¹, Hanxue Yan^{1

2}, Wenbo Gao^{1

2}, Qijun Pei¹, Anan Wu³, Ping Chen^{1

2}

Affiliations

¹ Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.

PMID: 34854674
DOI: 10.1021/jacs.1c09489

Abstract

Selective hydrogenation of alkynes to alkenes requires a catalytic site with suitable electronic properties for modulating the adsorption and conversion of alkyne, alkene as well as dihydrogen. Here, we report a complex palladium hydride, CaPdH₂, featured by electron-rich [PdH₂]^δ- sites that are surrounded by Ca cations that interacts with C₂H₂ and C₂H₄ via σ-bonding to Pd and unusual cation-π interaction with Ca, resulting in a much weaker chemisorption than those of Pd metal catalysts. Concomitantly, the dissociation of H₂ and hydrogenation of C₂H_x (x = 2-4) species experience significant energy barriers over CaPdH₂, which is fundamentally different from those reported Pd-based catalysts. Such a unique catalytic environment enables CaPdH₂, the very first complex transition-metal hydride catalyst, to afford a high alkene selectivity for the semihydrogenation of alkynes.