Synthesis and NMR investigation of 3,4-diazabicyclo[4.3.0]non-2-ene and N,N '-azo-3-azabicyclo[3.3.0]octane. X-ray crystal structure analysis of a new tetrazene derivative

3,4-Diazabicyclo[4.3.0]non-2-ene and N,N-azo-3-azabicyclo[3.3.0]octane are the main products of the oxidation of N-amino-3-azabicyclo[3.3.0]octane by chloramine. These new compounds have been isolated and characterized. A str uctural study has been performed with the goal of establishing the cis-tran s configuration at the bicyclic junction. Multinuclear proton decoupling ca rried out on the endocyclic hydrazone has allowed the determination of the coupling constant of the bridgehead hydrogens. A low temperature conformati onal study shows splitting of the C-13 signal of the carbon atom located a with respect to the ammonia nitrogen. This result, consistent with a cis st ructure, was confirmed by a nmr analysis conducted on the solid tetrazene d erivative. The X-ray data collection on a single crystal of the tetrazene h as permitted us to determine the crystallographic properties of this compou nd. Data processing by direct methods reveals that the geometry of the mole cule presents a cis configuration for the bicyclic bridge link and a trans one for the azo group, confirming thus the main results obtained by nmr stu dies.