Ab initio potential energy surface and electron correlation effect in CH activation of CH sub 4 by coordinatively unsaturated RhCl(PH sub 3 ) sub 2

Journal Article · Thu Jul 12 04:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100377a007· OSTI ID:6537319

Koga, Nobuaki; Morokuma, Keiji ^[1]

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1. Institute for Molecular Science, Okazaki (Japan)

Ab initio molecular orbital (MO) study of a model CH activation reaction, oxidative addition of CH{sub 4} to coordinatively unsaturated RhCl(PH{sub 3}){sub 2}, is presented. We have found that the reaction proceeds through a bifurcated ({eta}{sup 2}) CH{sub 4} complex, (CH{sub 4})RhCl(PH{sub 3}){sub 2}, and a three-centered transition state. At the highest level of calculation, MP4SDTQ, the reaction is exothermic by 24 kcal/mol relative to the isolated reactants and by 7 kcal/mol relative to the CH{sub 4} complex from which the activation barrier required is 3 kcal/mol. The CH{sub 4} complex is stabilized by the CH {yields} Rh d donation supplemented significantly by Rh {yields} CH{sub 4} back-donation as well as intermolecular (dispersion) and intramolecular electron correlation. The electron correlation is found to change the heat of reaction by 37 kcal/mol, thus shifting the location of transition state earlier and lowering the activation barrier drastically.

• OSTI ID: 6537319
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:14; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
033000* -- Natural Gas-- Properties & Composition
ALKANES
CALCULATION METHODS
CATALYSTS
CHEMICAL ACTIVATION
COMPLEXES
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HYDROCARBONS
MATHEMATICAL MODELS
METHANE
MOLECULAR ORBITAL METHOD
ORGANIC COMPOUNDS
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TRANSITION ELEMENT COMPLEXES