A 2:1 complex of 4-nitro-1,2-benzenediamine and 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6)

A 1:1 Host-Guest Complex between 1,4,7,10,13,16-Hexaoxacyclooctadecane ('18-crown-6') and m-Nitroaniline: Mere Stoicheiometry or a Genuine 1:1 Adduct ?

“…The overall arrangement of the adducts (see Fig. 2) is similar to those previously found [9,12,13]: Two nitroaniline molecules, related by a centre of inversion, are inclined with dihedral angles 66(1)° (for A) and 53(1)° (for B) 'above' and 'below' the planes formed by the six 0 atoms of the macrocycles (co-planar to within ± 26 pm in both crowns). Four strong and (possibly) two more very weak H bridges (Table V) link guest and host molecules in a pattern resembling that of 18-crown-6/^-nitroaniline 1:2 [11] (Fig.…”

“…1). This fact may favour disorder, especially if there is only one donor group in the molecule (in contrast to 4-nitro-l,2-benzenediamine [13]). …”

“…one guest molecule (or one donor group of a bifunctional guest molecule [5]) is attached to each side of the macrocycle. This also holds for the recently reported series of adducts with hydrazines [8,9] and anilines [10][11][12][13]. It was therefore surprising that elemental analysis [10] and cell volume of the title compound (V ca.…”

Intra- and Intermolecular Interactions in the Crystals of 3,4-Diamino-1,2,4-triazole and Its 5-Methyl Derivative. Experimental and Theoretical Investigations of Charge Density Distribution

“…Usually an amino group forms hydrogen bonds as a proton donor. However, some experimental and theoretical data − demonstrate that the nitrogen atom of the amino group can serve as a proton acceptor in the hydrogen bonds even despite the presence of n−π conjugation with participation of its lone pair.…”