Diazepines. Part 30.1 A Comparison between the Extent of Delocalisation of Electrons in a Vinamidine and its Protonated Form. Crystal and Molecular Structure of Two 2,3-Dihydro-1,4-diazepines

Synthesis and X-Ray Analysis of New 1,5-Benzodiazepinium Picrates

“…5 The compound crystallizes triclinic with one molecule of acetone of crystallisation ( Figure 1). The dihedral angles C(3)-C(4)-N(5)-C(6) = 13(2)° and C(11)-N(1)-C(2)-C(3) = -10.3(2)° confirm the slightly helical structure of the diazepinium moiety which was also found in 2,3-dihydro-1,4-diazepines 8 and mixed crystals consisting of 2,4-dimethylbenzodiazepinium and benzene-1,2-diammonium cations and chloride anions. 9 2,4-Dimethylbenzodiazepinium chloride 10 and hexafluorophosphate 11 as well as the hydrochloride of 2,4-dimethylnaphthodiazepine 12 are planar.…”

Mixtures obtained by reacting trans-(±)-1,2-diaminocyclohexane with acetylacetone in the presence of simple cobalt(II) salts

“…There does not appear to be much difference in the apparent delocalisation between these cationic and neutral diazepine species. In contrast, for phenyl-substituted diazepines there is a striking difference between bond distances in neutral diazepine bases and in their corresponding cations [14]. Although the cations have a definite delocalised structure, the bonds in the vinamidine systems of the diazepine bases are alternatively single and double.…”

Physico‐Chemical Properties of Organosuperbases

“…The strongest base is DBU, having values close to guanidines. Furthermore, it was found that in water dihydrodiazepine 64 has high basicity, the pK a value range is 13-14 units, due to the possession of a stable vinamidinium moiety in the conjugate acid [48]. X-ray crystallographic study showed the extensive p-electron delocalization in the vinamidinium portion of the molecule, with stabilization energy of about 19 kcal mol À1 .…”