Quantifying the Electronic Effect of C4 and C4′ Positions of Bipyridine Ligand on Pd(II)/Rh(I)-Catalyzed Conjugate Addition Reaction: A DFT Study |
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Authors: | Yao Jie Wei Zhang Jing-Yi Guo Hao Lu Hui-Ting Song Xin-Yu Xu Prof Hong Yan |
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Institution: | State Key Laboratory of Chemical, Resource Engineering, Beijing University of Chemical Technology, 100029 Beijing, P. R. China |
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Abstract: | The electronic effects of the bidentate ligands play a vital role in the transition metal-catalyzed conjugate addition reactions. Here, the insertion step (rate-determining step (RDS) of the conjugate addition) catalyzed by Pd(II)/Rh(I)-complexes with 26 bipyridine-type (bpy) ligands linking different substituent groups in the opposite sides (C4, C4′ position) are systematically studied by density functional theory (DFT). It is found that for both Pd(II)- and Rh(I)-catalysis, the stronger the electron-withdrawing group connecting to both C4 and C4′ positions of bpy ligands can promote the insertion step. The predominance of π-back donation in Rh(I) and σ-donation in Pd(II) is the main reason for above different electronic properties of Pd(II) and Rh(I)-catalysis. This work gives enough theoretical guide to the rational design of the efficient transition metal-based catalyst for conjugate addition. |
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Keywords: | transition metal catalysis conjugate addition reaction density functional theory theoretical studies ligand effects |
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