Table 3.

HOMO coefficients and charge densities for the selected atoms in 2–4 obtained by DFT-B3LYP calculations.

Compounds	2		3		4
HOMO (a.u.)	−0.221		−0.219		−0.210
Atoms	N1	N2	N1	N2	N1	N2	N3
HOMO coeff.	0.238	0.108	0.206	0.127	0.156	0.033	0.142
Charge density	−0.261	−0.187	−0.246	−0.201	−0.259	−0.148	−0.261