Theoretical Studies On The Structures And Properties Of High-nitrogen Heterocycle Compounds: Triazole And Tetrazine Derivatives

Triazoles and tetrazines are heterocycle compounds with high contents of nitrogen and high positive enthalpy of formation. Because of their high nitrogen and low carbon and hydrogen contents in molecular structures, they have large densities and are easy to reach oxygen balance. All these features and their low sensitivities are necessary for high-energetic density material (HEDM). Since the middle-later 90's of last century, many researchers have been paying more and more attention to them. But most of the related literatures are about experimental studies, there are few theoretical reports on triazoles and tetrazines. It is well-known that the tests of explosives are time-consuming, expensive and dangerous, moreover, there are many effect factors which cannot be forecasted. Therefore theoretical studies on the relations between structures and properties of triazoles and tetrazines are necessary and important for investigating and designing insensitive HEDM.In this dissertation, by using the density functional theory (DFT) B3LYP/6-311++G** method, we studied six parent triazoles and 38 triazole derivatives (ANTA homologs) systematically, gave their geometries, electronic structures and IR and presented the thermodynamics data by using the statistical thermodynamics theory. The substitutent effects of nitro-amino derivatives and nitroamine derivatives of triazoles and the relation between the structures and properties of triazole compounds were clarified. Nine triazole derivatives with relatively lower energies and higher stabilities were indicated. The intermolecular interactions in the dimers of four most stable triazole derivatives (4-amino-5-nitro-2H-l,2,3-triazole and three ANTA isomers) were studied, the relations of structures and properties were given and the characteristics of triazole derivatives including their geometries, electronic structures, IR and thermodynamics functions in changing from monomer to dimer in gas phase were revealed. By studying the solvation effects of six parent triazoles, we presented their solvation energies, compared the differences of every parameter in gas phase and solution, and discussed the effects of the polar organic solvent on their structures and properties.In addition, 17 tetrazine derivatives were studied at the B3LYP/6-311++G** level and their geometries, electronic structures, energies, IR, and thermodynamic functions were reported. Through analyzing the theoretical and experimental results, the relations between the structures and properties of tetrazine and it's derivatives were pointed out.By using the DFT and G2 results and designing reactions, the theoretical formation enthalpies of 55 title compounds were calculated. It is found that the conclusion...