A B3LYP AND MP2(FULL) THEORETICAL INVESTIGATION INTO THE C–NO2 BOND STRENGTH UPON THE FORMATION OF HF OR Na+ COMPLEX INVOLVING THE NITRO GROUP OF NITRO-1,2,4-TRIAZOLE

Abstract

The change of bond dissociation energy (ΔBDE) in the C–NO2 bond upon the formation of the intermolecular hydrogen-bonding or molecule-cation interaction between the nitro group of seven kinds of nitro-1,2,4-triazoles and HF or Na+ was investigated using the B3LYP and MP2(full) methods with the 6-311++G**, 6-311++G(2df, 2p) and aug-cc-pVTZ basis sets. The C–NO2 bond strength was enhanced and the charge of nitro group turned more negative in complex in comparison with those in isolated nitro-1,2,4-triazole molecule. The increment of the C–NO2 BDEs correlated well with the H-bonding interaction energy or molecule-cation interaction energy. The analysis of AIM, NBO and electron density shifts showed that the electron density shifted toward the C–NO2 bond upon complex formation, leading to the strengthened C–NO2 bond and the possibly reduced explosive sensitivity. The ΔBDE of the C–NO2 bond in the Na+ complex is far larger greater than that in the corresponding HF system. Thus, introducing cation into the structure of the nitrotriazole might be more efficacious to reduce explosive sensitivity than the formation of the intermolecular hydrogen-bonded complex.