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Theoretical Study of Stability, Molecular Structure and Intramolecular Hydrogen Bonding of an Energetic Molecule 1-phenyl-2-nitroguanidine: A Qtaim Approach

C. Theivarasu and Rangaswamy Murugesan

In the present work, ab initio and density functional theory (DFT) calculations are carried out on the energetic molecule 1-phenyl-2-nitroguanidine to understand its bond topology and its energetic properties using Bader’s atoms in molecules (AIM) theory. The optimized geometry predicts that the molecular structure of the compound is nonplanar, but contains two almost planar fragments: nitroguanyl group and phenyl group. The B3LYP/6-31G (d,p) theoretical level predicts that the electron density ρ(r) at the bond critical point of phenyl C-N bond is smaller than that of C-N bonds in nitroguanyl group. Based on the magnitude and sign of the Laplacian —2 ρ(r) and electron energy density he (r) at the critical points of bonds, the interactions are classified as covalent type of interaction in terms of atoms in molecules theory. The energy of the hydrogen bond is evaluated using the Espinoza’s formula. The electron energy density he(r) and – g(r)/v(r) value of hydrogen bond confirm the partly covalent nature of hydrogen bond. The impact sensitivity (90.5 cm) and oxygen balance (– 9.99%) were calculated and compared with energetic molecules. Large negative electrostatic potential regions were found near the nitro groups where reaction is expected to occur. The stability of compound was considered based on the values of the bond ellipticity and ESP.