AN ABINITIO STUDY OF SOME NITRAMINE MOLECULES

Ab initio self-consistent field (SCF) molecular orbital calculations have been performed for a series of nitramine molecules. Calculations were conducted on trinitramine, methyldinitramine, methylchloronitramine and trimethylamine using Pople's 6-31G and 6-31G* basis sets. Gas phase geometries for these molecules were determined by a minimum energy criterion using gradient techniques. The results are in qualitative agreement with the geometries derived from electron diffraction studies and microwave spectroscopy. The extra-long N-N bonds in methyldinitramine and methylchloronitramine were not computed accurately at the SCF level of theory and it was shown that these bonds become longer if electron correlation is included at the second-order Moller-Plesset level. Computations were performed for the heat of formation for trinitramine using Pople's isodesmic reaction concept and compared with a value obtained using an additivity rule.