Photochemical Activation of C-H Bonds on a Rhodium Catalyst. Observation of a Competitive Effect on the Surface

The UV (325 nm) photolysis of the Rh[sup 1](CO)[sub 2] species on an Al[sub 2]O[sub 3] support produces an active surface intermediate, Rh[sup 1](CO), which reacts with the C-H bond of cyclohexane by oxidative addition to form a postulated surface species, Rh(CO)(H)(C[sub 6]H[sub 11]). This species...

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Bibliographic Details
Published in:Journal of the American Chemical Society 1994-03, Vol.116 (5), p.1610-1615
Main Authors: Wong, Jason C. S, Yates, John T
Format: Article
Language:English
Subjects:
400102 - Chemical & Spectral Procedures
400500 - Photochemistry
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BOSONS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL BONDS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
CYCLOALKANES
CYCLOHEXANE
DECOMPOSITION
DIMERS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
Exact sciences and technology
General and physical chemistry
HYDROCARBONS
INFRARED SPECTRA
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MASSLESS PARTICLES
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
PHOTONS
Physical chemistry of induced reactions (with radiations, particles and ultrasonics)
RADIATIONS
RHODIUM COMPLEXES
SPECTRA
TRANSITION ELEMENT COMPLEXES
ULTRAVIOLET RADIATION
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Description
Summary:The UV (325 nm) photolysis of the Rh[sup 1](CO)[sub 2] species on an Al[sub 2]O[sub 3] support produces an active surface intermediate, Rh[sup 1](CO), which reacts with the C-H bond of cyclohexane by oxidative addition to form a postulated surface species, Rh(CO)(H)(C[sub 6]H[sub 11]). This species degrades to form a stable C[sub 6]H[sub 11] species on the surface. Unexpectedly, the normalized yield of surface C[sub 6]H[sub 11] species was found to be higher for lower Rh loadings using the same number of UV photons per unit area. This could be qualitatively explained by the fact that the formation of a dimer surface species, Rh[sub 2](CO)[sub 3] (a competitive reaction for the intermediate, Rh[sup 1](CO)[sub 7] responsible for C-H bond activation), is favored for high surface concentrations of Rh[sup 1](CO)[sub 2]. It is shown that the dimer formation competes with the desired C-H bond activation process. 41 refs., 9 figs., 1 tab.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00084a002