1. Quantum-Chemical Insight Into Mechanism of Combined Intra-Intermolecular Cycloaddition
- Author
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Milan Potáček, Jaroslav Koča, and Petr Kulhánek
- Subjects
Quantum chemical ,Reaction mechanism ,Molecular model ,010405 organic chemistry ,Chemistry ,Intermolecular force ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Cycloaddition ,0104 chemical sciences ,Computational chemistry ,Mechanism (philosophy) ,Density functional theory ,Basis set - Abstract
Two different reaction mechanisms of a mixed criss-cross cycloaddition with opposite sequence of reaction steps, intra-intermolecular and inter-intramolecular, were explored by quantum-chemical calculations at the MP2 and B3LYP levels of theory and with cc-pVDZ basis set. It was found that the rate-determining step in the both mechanisms is the first step regardless of the mechanism. The Gibbs activation barrier of the intramolecular step of the intra-intermolecular sequence is by 10.4 kcal mol-1 lower than that of the intermolecular step of the inter-intramolecular sequence at the MP2 level of theory and almost the same at the B3LYP level of theory. This together with known experimental data confirms that the intra-intermolecular sequence is the most probable mechanism.
- Published
- 2004