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A theoretical study of topomerization of imine systems: Inversion, rotation or mixed mechanisms?
Author(s) -
Gálvez Jesús,
Guirado Antonio
Publication year - 2010
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21323
Subject(s) - imine , isomerization , chemistry , transition state , ab initio , computational chemistry , inversion (geology) , rotation (mathematics) , crystallography , mathematics , organic chemistry , catalysis , geometry , paleontology , structural basin , biology
The different mechanisms, rotation, inversion, or intermediate mechanism, by which occur the topomerization of imine systems R 2 CNX have been studied by applying ab initio , B3LYP, and MP2 methods. The effect of a wide variety of substituents R and X on the isomerization pathway have been examined by computing fully optimized structures of the ground and transition states (136 isomers belonging to different imine families were studied and more than 300 transition structures were determined at various levels of theory). Energy barriers have been also obtained and it was found that the groups R and X have a strong influence on the type of mechanism involved and the activation energies. Thus, and depending on the type of substituents, transition state structures related to the following kinds of processes were found: pure inversion, intermediate mechanisms, rotation, and enhanced rotation (hyper‐rotation). In turn, the corresponding activation energies range between very low (<10 kcal/mol) and extremely high (> 70 kcal/mol) values. A simple index that allows us to quantify the percentage of inversion or rotation mechanism is proposed. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010