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σ and π contributions to the induced magnetic field: Indicators for the mobility of electrons in molecules
Author(s) -
Heine Thomas,
Islas Rafael,
Merino Gabriel
Publication year - 2006
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.20548
Subject(s) - electron , molecule , magnetic field , field (mathematics) , chemical physics , chemistry , computational chemistry , physics , quantum mechanics , mathematics , pure mathematics
The authors discuss the role of the σ and π contributions to the induced magnetic field for simple hydrocarbons containing a double or a triple bond, as well as for benzene and cyclobutadiene. While the magnetic field induced by the σ electrons is short‐ranged, the π system is responsible for the formation of long‐range cones. These cones influence the chemical shift of atoms by additional shielding (for aromatic) or deshielding (for antiaromatic molecules) contributions. While the hydrogen atoms of benzene are found to lie within the deshielded region of the magnetic field induced by the π electrons, they are shielded by the total induced magnetic field. The induced magnetic field of the π electrons support Pople's model on the basis of first‐principles calculations. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007