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An analysis of the isomerization energies of 1,2-/1,3-diazacyclobutadiene, pyrazole/imidazole, and pyridazine/pyrimidine with the turn-upside-down approach

The isomerization energies of 1,2- and 1,3-diazacyclobutadiene, pyrazole and imidazole, and pyridazine and pyrimidine are 10.6, 9.4, and 20.9 kcal/mol, respectively, at the BP86/TZ2P level of theory. These energies are analyzed using a Morokuma-like energy decomposition analysis in conjunction with what we have called turn-upside-down approach. Our results indicate that, in the three cases, the higher stability of the 1,3-isomers is not due to lower Pauli repulsions but because of the more favorable σ-orbital interactions involved in the formation of two C-N bonds in comparison with the generation of C-C and N-N bonds in the 1,2-isomers

We thank the following organizations for financial support: the Ministerio de Ciencia e Innovacion (MICINN, Project Nos. CTQ2008-03077/BQU, CTQ2008-06532/BQU, and CTQ2011-23156/BQU, Ramon y Cajal contract to J.P., and FPI fellowship to M.E.H.) and the DIUE of the Generalitat de Catalunya (project no. 2009SGR637). W.T. thanks FONDECYT (Grant No. 1109043). We acknowledge helpful comments from Prof. Dr. F. Matthias Bickelhaupt. Excellent service by the Centre de Supercomputacio de Catalunya (CESCA) is gratefully acknowledged

© Journal of Organic Chemistry, 2011, vol. 76, núm. 21, p. 8913-8921

American Chemical Society (ACS)

Autor: El Hamdi Lahfid, Majid
Tiznado, William
Poater i Teixidor, Jordi
Solà i Puig, Miquel
Data: 4 novembre 2011
Resum: The isomerization energies of 1,2- and 1,3-diazacyclobutadiene, pyrazole and imidazole, and pyridazine and pyrimidine are 10.6, 9.4, and 20.9 kcal/mol, respectively, at the BP86/TZ2P level of theory. These energies are analyzed using a Morokuma-like energy decomposition analysis in conjunction with what we have called turn-upside-down approach. Our results indicate that, in the three cases, the higher stability of the 1,3-isomers is not due to lower Pauli repulsions but because of the more favorable σ-orbital interactions involved in the formation of two C-N bonds in comparison with the generation of C-C and N-N bonds in the 1,2-isomers
We thank the following organizations for financial support: the Ministerio de Ciencia e Innovacion (MICINN, Project Nos. CTQ2008-03077/BQU, CTQ2008-06532/BQU, and CTQ2011-23156/BQU, Ramon y Cajal contract to J.P., and FPI fellowship to M.E.H.) and the DIUE of the Generalitat de Catalunya (project no. 2009SGR637). W.T. thanks FONDECYT (Grant No. 1109043). We acknowledge helpful comments from Prof. Dr. F. Matthias Bickelhaupt. Excellent service by the Centre de Supercomputacio de Catalunya (CESCA) is gratefully acknowledged
Format: application/pdf
ISSN: 0022-3263 (versió paper)
1520-6904 (versió electrònica)
Accés al document: http://hdl.handle.net/10256/11390
Llenguatge: eng
Editor: American Chemical Society (ACS)
Col·lecció: MEC/PN 2009-2011/CTQ2008-03077
MEC/PN 2009-2011/CTQ2008-06532
MICINN/PN 2012-2014/CTQ2011-23156
AGAUR/2009-2014/2009 SGR-637
Reproducció digital del document publicat a: http://dx.doi.org/10.1021/jo201639k
Articles publicats (D-Q)
És part de: © Journal of Organic Chemistry, 2011, vol. 76, núm. 21, p. 8913-8921
Drets: Tots els drets reservats
Matèria: Isomerització
Isomerization
Títol: An analysis of the isomerization energies of 1,2-/1,3-diazacyclobutadiene, pyrazole/imidazole, and pyridazine/pyrimidine with the turn-upside-down approach
Tipus: info:eu-repo/semantics/article
Repositori: DUGiDocs

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