Theoretical studies on four-membered ring compounds with NF₂, ONO₂, N₃, and NO₂ groups

• Published in: Journal of computational chemistry Vol. 29; no. 4; pp. 505 - 513
• Main Authors: Fan, Xiao-Wei, Ju, Xue-Hai
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.03.2008
• Subjects: bond dissociation energy; density functional theory; detonation pressure; detonation velocity; Electrons; Fluorine - chemistry; four-membered ring compounds; heats of formation; Heterocyclic Compounds, 1-Ring - chemistry; homodesmotic reaction; Hot Temperature; intramolecular group interaction; isodesmic reaction; Models, Chemical; Molecular Structure; Nitrogen - chemistry; Nitrogen Dioxide - chemistry; strain energy
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.20809

Density functional theory (DFT) method has been employed to study the geometric and electronic structures of a series of four-membered ring compounds at the B3LYP/6-311G** and the B3P86/6-311G** levels. In the isodesmic reactions designed for the computation of heats of formation (HOFs), 3,3-dimethyl-oxetane, azetidine, and cyclobutane were chosen as reference compounds. The HOFs for N₃ substituted derivations are larger than those of oxetane compounds with ---ONO₂ and/or ---NF₂ substituent groups. The HOFs for oxetane with ---ONO₂ and/or ---NF₂ substituent groups are negative, while the HOFs for N₃ substituted derivations are positive. For azetidine compounds, the substituent groups within the azetidine ring affect the HOFs, which increase as the difluoroamino group being replaced by the nitro group. The magnitudes of intramolecular group interactions were predicted through the disproportionation energies. The strain energy (SE) for the title compounds has been calculated using homodesmotic reactions. For azetidine compounds, the NF₂ group connecting N atom in the ring decrease the SE of title compounds. Thermal stability were evaluated via bond dissociation energies (BDE) at the UB3LYP/6-311G** level. For the oxetane compounds, the O---NO₂ bond is easier to break than that of the ring C---C bond. For the azetidine and cyclobutane compounds, the homolysises of C---NX₂ and/or N---NX₂ (X = O, F) bonds are primary step for bond dissociation. Detonation properties of the title compounds were evaluated by using the Kamlet-Jacobs equation based on the calculated densities and HOFs. It is found that 1,1-dinitro-3,3-bis(difluoroamino)-cyclobutane, with predicted density of ca. 1.9 g/cm³, detonation velocity (D) over 9 km/s, and detonation pressure (P) of 41 GPa that are lager than those of TNAZ, is expected to be a novel candidate of high energy density materials (HEDMs). The detonation data of nitro-BDFAA and TNCB are also close to the requirements for HEDMs. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008