COMPARISION STUDY OF VIBRATION FREQUENCIES WITH BOND ORDERS OF CH AND CC BONDS IN CORONENE AND IT'S POSITIVE AND NEGATIVE RADICAL IONS USING QUANTUM MECHANICAL CALCULATIONS

Abstract

Vibration frequencies, IR absorption intensities and normal coordinates of theCoronene radical cation and anion were calculated applying the semiemperical methods MINDO/3 andPM3, and quantum mechanical method (DFT (B3LYP/6-311G)). The results allowed properassignments for the frequencies of the experimentally known, radical cation vibrations. They providedpreestimation of the radical anion frequencies. Comparison is done for the frequencies of the ions withthose of the neutral Coronene molecule. It was found that the C-H stretching frequencies are directlyrelated to the carbon -electron densities of the relevant atoms. This is not true for the change in theCC stretching frequencies, which seem to be due to the change in symmetry from D6h for the neutralmolecule to D2h for its positive and negative radical ions