The charges at the C 2 and C 3 atoms showed the greatest changes based on the nature of the substituents. The negative charge at C 2 decreased from 1a to 1g and it became positive at 1h. The charge at C 3 was positive for 1a and 1b and became slightly negative at 1c, then increased in the order of 1d < 1e < 1f < 1g <1h. Although, the negative charge at C 2 for 1i was relatively high, the negative charge at C 3 was found between the values observed for 1e and 1f.