Gold catalyzed hydrogenations of small imines and nitriles: enhanced reactivity of Au surface toward H2via collaboration with a Lewis base

Gang Lu; Peng Zhang; Dongqing Sun; Lei Wang; Kebin Zhou; Zhi-Xiang Wang; Guo-Cong Guo

doi:10.1039/C3SC52851K

Gold catalyzed hydrogenations of small imines and nitriles: enhanced reactivity of Au surface toward H₂via collaboration with a Lewis base†

Gang Lu,^ab Peng Zhang,^a Dongqing Sun,^a Lei Wang,^a Kebin Zhou,^a Zhi-Xiang Wang*^ac and Guo-Cong Guo*^b

* Corresponding authors

^a College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing, P. R. China
E-mail: zxwang@ucas.ac.cn, gcguo@fjirsm.ac.cn

^b State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China

^c Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, P. R. China

Abstract

Clean gold surface is inactive toward H₂, however, computations, aided by experiments, reveal that gold surface could serve as a Lewis acid coupling with Lewis bases (e.g. imine and nitrile) to construct effective frustrated Lewis pairs (FLPs) to activate H₂ and subsequently to achieve hydrogenation of small imines and nitriles. The Lewis base-coupled Au FLPs avoid tight adsorption of Lewis bases to gold surface via repulsion between nitrogen lone pair and the filled d-band electrons of the gold surface. This is different from the normal FLPs that use sterically demanding groups or a molecular scaffold to prevent formation of stable Lewis acid–base complexes. The enhanced reactivity of the gold surface toward H₂ is due to the synergetic catalytic effects of Lewis acid (Au surface) and the coupled Lewis base (imine or nitrile), which is supported by projected density of states (PDOS) analyses. Among Cu, Ag and Au surfaces, Au surface exhibits such reactivity most significantly, because Au is much more electronegative than Cu and Ag. The study enriches the FLP chemistry by adding a new type (heterogeneous) of FLPs and reveals a new reaction mode for gold surface.

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Article information

DOI: https://doi.org/10.1039/C3SC52851K
Article type: Edge Article
Submitted: 14 Oct 2013
Accepted: 19 Nov 2013
First published: 21 Nov 2013

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Chem. Sci., 2014,5, 1082-1090

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Gold catalyzed hydrogenations of small imines and nitriles: enhanced reactivity of Au surface toward H₂via collaboration with a Lewis base

G. Lu, P. Zhang, D. Sun, L. Wang, K. Zhou, Z. Wang and G. Guo, Chem. Sci., 2014, 5, 1082 DOI: 10.1039/C3SC52851K

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