AZIDOPENTAZOLE IS PROBABLY THE LOWEST-ENERGY N-8 SPECIES - A THEORETICAL-STUDY

Ab initio molecular orbital calculations at the quadratic configuratio n interaction [QCISD(T)/G-31G(d)] and coupled-cluster theory [CCSD(T)/ DZP] levels based on MP2/6-31G(d) optimized geometries show that azido pentazole is Likely to be the global minimum of the N-8 isomers lying 13 and 18 kcal/mol below the acyclic diazidyldiimide and the cyclic pe ntalene analogue, respectively. Azidopentazole is characterized by a s ignificant energy barrier to ring closure and is expected to be stable with respect to cycloreversion and thus constitutes the most realisti c N-8 target for a synthetic preparation.