A theoretical study of X ligand effect on catalytic activity of complexes RuHX(diamine)(PPh3)2 (X = NCMe, CO, Cl, OMe, OPh, CCMe and H) in H2-hydrogenation of ketones

Zhuo Chen; Yue Chen; Yanhui Tang; Ming Lei

doi:10.1039/B917934H

A theoretical study of X ligand effect on catalytic activity of complexes RuHX(diamine)(PPh₃)₂ (X = NCMe, CO, Cl, OMe, OPh, CCMe and H) in H₂-hydrogenation of ketones†

Zhuo Chen,^a Yue Chen,^a Yanhui Tang^b and Ming Lei*^a

* Corresponding authors

^a State Key Laboratory of Chemical Resource Engineering, Institute of Materia Medica, College of Science, Beijing University of Chemical Technology, Beijing, PR China
E-mail: leim@mail.buct.edu.cn
Fax: +86(10)64446598
Tel: +86(10)64446598

^b School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing, PR China
E-mail: yanhui_tang@hotmail.com
Fax: +86(10)64284087
Tel: +86(10)64446598

Abstract

In this paper, the catalytic activities of RuHX(diamine)(PPh₃)₂ complexes with different X ligands (X = NCMe, CO, Cl, OMe, OPh, CCMe and H, corresponding catalytic processes are abbreviated in A, B, C, D, E, F and G systems, respectively) in the H₂-hydrogenation of ketones were investigated using density functional theory (DFT) method. Calculated results indicate that the rate-determining step in the whole catalytic cycle is hydrogen transfer (HT) for A–E but dihydrogen activation (DA) for F and G. The free energy barriers of the HT step for A–G are 36.1, 32.3, 21.2, 14.9, 21.9, 9.4 and 6.9 kcal mol⁻¹, respectively. The DA step consists of hydrogen coordination (HC) and hydrogen splitting (HS) steps if dihydrogen coordinates with the Ru center. The transition states (TSs) of H₂ coordinating with the Ru atom for A–G except B are located. The free energy barriers of DA for A–G are 17.8 (17.8, 2.6), 21.5, 12.8 (12.8, 3.8), 12.2 (11.2, 6.2), 13.6 (13.6, 4.1), 17.1 (9.7, 7.5) and 22.0 (10.4, 11.0) kcal mol⁻¹, respectively (the data in parentheses correspond to the barriers of HC and HS). HT barriers correlate well with the charges of hydride (H) in complex 1. HC barriers are closely related to the Ru [double bond, length as m-dash] N¹ double bond in 4, and HS are in line with the proton-moved-distances (PMDs) from 5 to TS5-1. This study demonstrates that catalysts D, F and G show better catalytic activities than the others, which is in good agreement with experimental results.

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Article information

DOI: https://doi.org/10.1039/B917934H
Article type: Paper
Submitted: 01 Sep 2009
Accepted: 26 Nov 2009
First published: 13 Jan 2010

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Dalton Trans., 2010,39, 2036-2043

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A theoretical study of X ligand effect on catalytic activity of complexes RuHX(diamine)(PPh₃)₂ (X = NCMe, CO, Cl, OMe, OPh, CCMe and H) in H₂-hydrogenation of ketones

Z. Chen, Y. Chen, Y. Tang and M. Lei, Dalton Trans., 2010, 39, 2036 DOI: 10.1039/B917934H

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