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Ab initio and experimental thermodynamic and kinetic study of proton-assisted bond activation in gaseous hydrocarbons: deconvolution of reaction efficiencies in the case of adamantane.

Dávalos JZ, Herrero R, Quintanilla E, Jiménez P, Gal JF, Maria PC, Abboud JL

Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid, Spain.

1) Protonation at all possible sites of adamantane (C(10)H(16)) was studied at the MP2/6-311++G(3df,2p)//MP2/6-311++G(d,p) level. This provided values of the changes in the thermodynamic state functions for these processes. Whenever direct comparison was possible, the agreement with experimental data was very good. 2) By the same means, the reaction paths linking the various species obtained in these reactions were analyzed. 3) Fourier transform ion cyclotron resonance (FT-ICR) spectroscopy was used to determine the rate constants for proton transfer from 16 protonated reference bases to adamantane in the gas phase. Also, the rate constants for the formation of ionic products in these reactions were determined. 4) The experimental reaction rates were successfully predicted and refined on the basis of a simple mechanistic model based on the reaction profiles indicated above. 5) Our results hint at the potential usefulness of this approach for mechanistic studies.

Published 14 August 2006 in Chemistry, 12(21): 5505-13.
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