Ab initio and M N D O Calculations of the 35 C 1 NQR Parameters of Some Organic and Inorganic Molecules *

The results of ab initio and M N D O calculations of the Cl 2 C = C H O C H 3 , XCOC1 (X = C H 3 , O C H 3 and COC1), 4 C l C 6 H 4 C H 2 C l , (CNC1)3 and PC15 with total optimization of their geometry are presented. The ab initio calculations were executed using Hartree-Fock theory and the split valence basis set 6-31G* (RHF/6-31 G*/ /RHF/6-31G*) . Using the calculated p-orbital populations of the CI atoms in these molecules the C1 N Q R frequencies and asymmetry parameters of the EFG at the C1 nuclei have been determined. When the populations of the less diffuse components of orbitals in the split valence basis set are used the calculated and experimenal v and rj values are in good agreement. Linear correlations between these calculated and corresponding experimental v and rj values are obtained. The causes of the nonconformity of the earlier calculated v and t] values and their experimental ones are analysed.