Affiliations: Department of Chemistry, Amirkabir University of
Technology, Tehran, Iran
Note: [] Corresponding author: Zahra Shariatinia, Department of
Chemistry, Amirkabir University of Technology, P. O. Box 159163-4311, Tehran,
Iran. Tel.: +98 2164543295; Fax: +98 2164543296; E-mail: shariati@aut.ac.ir
Abstract: The hydrogen bonding interactions between both 1R-2R and 1S-2S
isomers of pseudoephedrinium cation (Drug) and methacrylicacid (MAA) were
calculated using Gaussian 98 software. Eight possible forms for the
H-bond interactions were computed at HF and B3LYP levels of theory with
6-31G(d) and 6-31+G(d,p) basis sets and for all of the
molecules the B3LYP/6-31G* provides the highest stabilization energies. The
hydrogen bonding energies, E_{(H-bond)}, were obtained
from the equation E_{(H-bond)}=E_{(complex)} – [E_{(Drug}}+
E_{(MAA)}] and among four
computational methods, B3LYP/6-31G(d) provides the highest hydrogen bonding
energy for all of the complexes. The nuclear quadrupole coupling constants
(χ) for ^{17}O, tetrahedral
^{14}N nuclei were calculated about 10.0, 0.5–1.0 MHz and
for ^{2}H atoms varied from nearly 150.0 kHz to almost 350.0 kHz.
Keywords: Ab initio computations, pseudoephedrinium cation, hydrogen bonding interactions, NQR
