Anomalous Energy Effects Associated with the Presence of Aza Nitrogens and Nitro Substituents in Some Strained Systems

We have used an ab initio SCF molecular orbital approach in conjunction with the isodesmic reaction procedure to investigate anomalous energy effects in strained aza systems and some of their nitro derivatives. The introduction of nitrogens into strained molecular frameworks is found to confer added degrees of stability. In general this increases with the number of nitrogens in a series of similar molecules. Further stabilization results from N-nitro substitution and the mononitration of secondary carbons; however the polynitration of systems containing highly strained tertiary carbons has a marked destabilizing effect.