Thermochemistry, energy comparisons, and conformational analysis of hydrazine, triazane, and triaminoammonia

The series NH 3 , H 2 NNH 2 , HN(NH 2 ) 2 (triazane), and N(NH 2 ) 3 (triaminoammonia) has been studied by computational methods (HF/6-31G * and MP2/6-31G * optimizations for all species, G2 (see paragraphoncomputations) energies for the most stable form of each molecule). Thermodynamic functions have been computed. Structural aspects have been discussed in terms of stabilizing and destabilizing factors. The importance of hydrogen bonding and hyperconjugation has been discussed on the basis of potential surface differences and vibrational spectra. Relative stabilities have been discussed from isodesmic reaction schemes, from which also the following estimates of N-N bond energy are obtained: hydrazine, 64 kcal/mol; triazane, 66 kcal/mol; triaminoammonia, 59 kcal/mol