Azidopentazole is Probably the Lowest‐Energy N8 Species – A Theoretical Study

Ab initio molecular orbital calculations at the quadratic configuration interaction [QCISD(T)/6‐31G(d)] and coupled‐cluster theory [CCSD(T)/DZP] levels based on MP2/6‐31G(d) optimized geometries show that azidopentazole is likely to be the global minimum of the N8 isomers lying 13 and 18 kcal/mol below the acyclic diazidyldiimide and the cyclic pentalene analogue, respectively. Azidopentazole is characterized by a significant energy barrier to ring closure and is expected to be stable with respect to cycloreversion and thus constitutes the most realistic N8 target for a synthetic preparation.