X-Ray crystal structure determination of a series of 1-aryl- 2-[3-(3-[2-aryl-1-diazenyl]-1,3-diazepan-1-ylmethyl)-1, 3-diazepan-1-yl]-1-diazenes obtained from the reaction of diazonium salts with mixtures of formaldehyde and 1,4-diaminobutane

A new series of bis-triazenes, the 1-aryl-2-[3-(3-[2-aryl-1-diazenyl]-1,3-diazepan-1-ylmethyl)-1,3-diazepan-1-yl]-1-diazenes has been synthesized from the reaction of diazonium salts with a mixture of 1,4-diaminobutane and formaldehyde. The structures of 1-(p-bromophenyl)-2-[3-{3-[2-(p-bromophenyl)-1-diazenyl]-1,3-diazepan-1-ylmethyl}-1,3-diazepan-1-yl]-1-diazene(1), 1-(p-cyanophenyl)-2-[3-{3-[2-(p-cyanophenyl)-1-diazenyl]-1,3-di azepan-1-ylmethyl}-1,3-diazepan-1-yl]-1-diazene(2), and 1-(p-methoxyphenyl)-2-[3-{3-[2-(p-methoxy-phenyl)-1-diazenyl]-1,3-diazepan-1-ylmethyl}-1,3-diazepan-1-yl]-1 diazene(3) have been unequivocally determined by X-ray crystallography. The new bis-triazenes are important since the structure contains the novel saturated heterocycle, 1,3-diazepane. The general conclusion of this study is that alkanediamines with 3 or 4 carbon atoms in the spacer link between the nitrogen atoms give rise to the linear bicyclic molecules of type 5, in contrast to the case of ethylenediamine (spacer link 2 carbon atoms), which affords molecules of type 6, which exemplify the general cage structure of type 4. The crystal structures of 1, 2 and 3 are compared with the previously reported structure of the hexahydropyrimidine analogue 8a(X=CN); compounds 2 and 8a(X=CN) are homologous with respect to the alkane spacer moiety. The structures of 2 and 8a(X=CN) are very different in one respect; in 2 the aryldiazenyl-1,3-diazepanyl groups are in the s-trans orientation around the central methylene group whereas in 8a(X=CN) the arrangement of the aryldiazenyl-hexahydropyrimidinyl groups is the s-cis orientation.

Crystal data: 1 C₂₃H₃₀N₈Br₂, triclinic, space group P-1, a=8.3979(2), b=10.7828(3), c=14.4692(5) Å, α=83.670(1), β=78.662(1), γ=78.758(1)°, V=1256.48(6) ų, for Z=2. 2 C₂₅H₃₀N₁₀, monoclinic, space group P2 ₁ /n, a=13.4046(6), b=9.4482(4), c=10.6913(4)Å, β=103.239(2)°, V=2490.5(2) ų, for Z=4. 3 C₂₅H₃₆N₈O₂, triclinic, space group P-1, a=8.5223(3), b=10.6913(4), c=14.4034(7)Å, α=85.657(2), β=78.731(2), γ=80.153(1)°, V=1266.88(9) ų, for Z=2.