jp9062516_si_002.xls (398 kB)

Exploring 1,2-Hydrogen Shift in Silicon Nanoparticles: Reaction Kinetics from Quantum Chemical Calculations and Derivation of Transition State Group Additivity Database

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posted on 15.10.2009, 00:00 by Andrew J. Adamczyk, Marie-Francoise Reyniers, Guy B. Marin, Linda J. Broadbelt
Accurate rate coefficients for 35 1,2-hydrogen shift reactions for hydrides containing up to 10 silicon atoms have been calculated using G3//B3LYP. The overall reactions exhibit two distinct barriers. Overcoming the first barrier results in the formation of a hydrogen-bridged intermediate species from a substituted silylene and is characterized by a low activation energy. Passing over the second barrier converts this stable intermediate into the double-bonded silene. Values for the single event Arrhenius pre-exponential factor, , and the activation energy, Ea, were calculated from the G3//B3LYP rate coefficients, and a group additivity scheme was developed to predict and Ea. The values predicted by group additivity are more accurate than structure/reactivity relationships currently used in the literature, which rely on a representative value and the Evans−Polanyi correlation to predict Ea. The structural factors that have the most pronounced effect on and Ea were considered, and the presence of rings was shown to influence these values strongly.

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