Issue 1, 2017

Ethene hydrogenation vs. dimerization over a faujasite-supported [Rh(C2H4)2] complex. A computational study of mechanism

Abstract

Single-site catalysts offer great chances for unraveling the mechanism and the selectivity of catalytic mechanism, in particular when the system is experimentally well characterized. A particular interesting system of this type is the hydrogenation and the dimerization of ethene by the faujasite-supported complex [Rh(C2H4)2]+. We have examined this system computationally, treating periodic models with a density functional method. The complex [Rh(C2H4)2]+ binds in a bidentate fashion, as previously suggested, inside the faujasite supercage at the oxygen atoms of a 12-member ring. The calculations on this model complex showed ethene hydrogenation to be preferred over dimerization. The highest free energy barrier for forming a C–H bond was calculated at 33 kJ mol−1 at room temperature. This value is significantly lower than the lowest activation free energy, 97 kJ mol−1, calculated for C–C bond formation. The results of this mechanistic study allow one to rationalize the experimental observation that the faujasite-supported [Rh(C2H4)2]+ complex in the presence of H2 is active for hydrogenation, producing ethane as the main product.

Graphical abstract: Ethene hydrogenation vs. dimerization over a faujasite-supported [Rh(C2H4)2] complex. A computational study of mechanism

Supplementary files

Article information

Article type
Paper
Submitted
11 Oct 2016
Accepted
16 Nov 2016
First published
28 Nov 2016

Catal. Sci. Technol., 2017,7, 102-113

Ethene hydrogenation vs. dimerization over a faujasite-supported [Rh(C2H4)2] complex. A computational study of mechanism

A. Govindasamy, V. K. Markova, A. Genest and N. Rösch, Catal. Sci. Technol., 2017, 7, 102 DOI: 10.1039/C6CY02147F

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