Synthesis and Characterization of Novel Bis-Triazenes:  3,8-Di[2-aryl-1-azenyl]-1,3,6,8-tetraazabicyclo[4.4.1]undecanes and 1,3-Di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine. The Reaction of Diazonium Ions with Ethylenediamine/Formaldehyde Mixtures

Reaction of a diazonium salt solution with a mixture of ethylenediamine and an excess of formaldehyde or 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane results in the formation of a novel class of bis-triazenes, the 3,8-di(2-aryl-1-azenyl)-1,3,6,8-tetraazabicyclo[4.4.1]undecanes (6), which have been fully characterized by spectroscopy, elemental analysis, and X-ray crystallography. The X-ray data show that the tetraazabicyclic cage is folded back so that the aryl groups interact by π−π-stacking. The proton NMR spectra are made complex by the presence of three sets of distinctly different diastereotopic methylene groups, which have been assigned by a combination of decoupling and 2D-NMR experiments. In the case involving coupling of the p-anisidine diazonium derivative to ethylenediamine and formaldehyde mixtures, 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine (8) was the only product isolated. Its structure has been assigned on the basis of 1H and 13C NMR spectra and X-ray crystallography.