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A theoretical study of conformational flexibility, magnetic properties, and polarizabilities of trimethylnaphthalenes

Authors

  • Bojana D. Ostojić,

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    • Department of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Belgrade 11 000, Serbia
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  • Slobodan Mišić,

    1. Department of Mathematics, Physics and Descriptive Geometry, Faculty of Civil Engineering, University of Belgrade, Belgrade 11000, Serbia
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  • Dragana S. Đorđević

    1. Department of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Belgrade 11 000, Serbia
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Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade 11 000, Serbia. E-mail: bostojic@chem.bg.rs

Abstract

For almost all trimethylnaphthalenes (TMNs), the transition from a planar equilibrium ring conformation to a nonplanar conformation characterized by the torsional angle of 20° results in an energy increase of less than 2.5 kcal/mol. For some of them, it is less than 1.6 kcal/mol, which indicates that these molecules can change their conformation easily through intermolecular interactions. The results of the calculations reveal a linear relationship between the averaged rigidity constant and the relative energy for all planar TMNs. The changes of rings deformational energy imposed on π-electron systems of TMNs by medium polarity are negligible (less than 0.05 kcal/mol). The aromaticity indices, based on nucleus-independent chemical shifts, indicate aromatic character of TMNs. The α substitution increases the ring area more than the β substitution. The increase of anisotropy of dipole polarizabilities with the decrease of the area of rings for all planar TMNs, dimethylnaphthalenes and methylnaphthalenes is noticed. © 2013 Wiley Periodicals, Inc.

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