COMPARATIVE COMPUTATIONAL ANALYSIS OF SOME NITRAMINE AND DIFLUORAMINESTRUCTURES, DISSOCIATION-ENERGIES AND HEATS OF FORMATION

Density functional methods have been used to compute the optimized geo metries, dissociation energies and gas phase heats of formation of sev eral difluoramines (in which the -NF2 is attached to a nitrogen) and t he corresponding nitramines. The -NF2 groups are found to be pyramidal , in contrast to the planarity of -NO2. In each instance, one N-F bond length is at least 0.1 Angstrom longer than the other while the N-N b onds are anomalously short. For the molecules and properties studied, the effects of -NO2 and -NF2 (on nitrogen) do not differ dramatically. Replacing > N-NO2 by > N-NF2 affects the dissociation energies of oth er N-NO2 and C-NO2 bonds only slightly (2-3 kcal mol(-1)); however the N-NF2 bonds are 3-6 kcal mol(-1) stronger than the N-NO2 that were re placed. The difluoramine heats of formation are less positive, by 15-1 7 kcal mol(-1), than those of the corresponding nitramines.