Natural population analysis was carried out for EDB. Negative characters for N and O atoms in the N-C-(H)•••O-I conjunction and positive character for H atom confirms the hydrogen bonding between two (three) molecules.

The energy gaps are largely responsible for the chemical and spectroscopic properties of the molecules. LUMO–HOMO energy gap in gaseous phase is accordance to R1>R3>R2. These trend is accordance to experimental ...

are in excellent agreement with the experimental data. HOMOeLUMO energies and natural charges over chelated ring atoms of Cu(APBO)2 and Cu(APO)2 are also compared....