Quantum mechanical investigation of the charge transfer molecular complexes of methimazole with I-2, IBr and ICl
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Papayannis, D. K.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
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Papayannis, D. K.
(EN)
The structural, frequency and energy characteristics and the nature of bonding of the molecular complexes between N-methyl imidazoline-2-thione (methimazole) and the related saturated analog, N-methyl imidazolidine-2-thione and the dihalogens IY (Y = Cl, Br, I) are investigated using quantum mechanical computational techniques. Two types of stereoisomeric energy minima have been studied for each parent thioamide system. Both present a collinear S-I-Y geometry and are distinguished by the geometry of the dihalogen IY molecular axis located at either a planar or a perpendicular arrangement with respect to the imidazolethione, NCS, plane. The planar conformations have been found to be more stable than the perpendicular ones, since they allow a more favourable geometry for an additional interaction between the iodine atom and the amidic H. The results reveal interesting correlations of various structural and frequency features like the C-S and S-I bonding distances and the N-H stretching frequency shifts with the enthalpy of complexation, the electron donor acceptor capacity of the dihalogen and the electronegativity of the Y atom and the strength of the interaction between the amidic hydrogen and the inner I. (c) 2007 Elsevier B.V. All rights reserved.
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