A THEORETICAL INVESTIGATION OF SUBSTITUENT EFFECTS ON STRUCTURE AND NQR PARAMETERS OF PHENACYL PHENYL SULFIDE DERIVATIVES

Abstract

This paper describes a theoretical investigation of the geometrical parameters and the 17 O and 33 S nuclear quadrupole resonance (NQR), parameters of phenacyl phenyl sulfide derivatives. The calculations were carried out using Gaussian 98 package by applying the Hartree–Fock method (HF), the second-order Møller–Plesset perturbation theory (MP2), and the density functional theory (DFT) and by employing the 3-21G, 6-31G, and 6-311G basis sets in the Townes–Daily approximation. It was shown that all of the methods can be used to predict the NQR parameters; however, the DFT is the best method of all the methods in use. The nuclear quadrupole coupling constants, CQ, and the asymmetry parameter, η, were calculated for all of the nuclei in each molecule, separately. The results indicated that the value of CQ and η for 17 O nucleus increases in the order of H > Br > NH 2 > CH 3 and NH 2 > H > Br > CH 3, respectively, as well as, for the 33 S nucleus the increase in the order of substituents was NH 2 > H > Br CH 3 and CH 3 > H > Br > NH 2, respectively.