Acta Crystallographica Section B

Structural Science

Volume 56, Part 6 (December 2000)

research papers

Acta Cryst. (2000). B56, 1054-1062 [ doi:10.1107/S0108768100008302 ]

Adducts of meso and racemic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane with trigonally trisubstituted benzene carboxylic acids: supramolecular structures in one and two dimensions

C. J. Burchell, G. Ferguson, A. J. Lough and C. Glidewell

Abstract: The meso and racemic forms of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, C₁₆H₃₆N₄ (tet-a and tet-b, respectively), form adducts with trigonally trisubstituted benzene carboxylic acids; tet-a-3,5-dinitrobenzoic acid (1/2) (1), tet-a-5-hydroxyisophthalic acid-water (1/1/1) (3) and tet-b-5-hydroxyisophthalic acid-water (1/1/1) (4) are all salts, [C₁₆H₃₈N₄]²⁺·2[C₇H₃N₂O₆]^- (1) and [C₁₆H₃₈N₄]²⁺·[C₈H₄O₅]^2-·H₂O (3) and (4). The conformations of the [(tet-a)H₂]²⁺ and [(tet-b)H₂]²⁺ cations are entirely different: [(tet-a)H₂]²⁺ is precisely centrosymmetric in (1) and approximately so in (3), while [(tet-b)H₂]²⁺ has approximate C₂ symmetry in (4). In each salt the cation forms two intramolecular N-HN and four intermolecular N-HO hydrogen bonds. In (1) the supramolecular structure is one-dimensional, a C₂²(13)[R₂⁴(16)] chain of rings. Compounds (3) and (4) crystallize in space groups P2₁2₁2₁ and P2₁/c, respectively, but the supramolecular structures are very similar: in each, the anions and the water molecules form a C(7)[R₃³(13)] chain of rings, generated in (3) by a 2₁ axis and in (4) by a glide plane. These chains are linked, in both (3) and (4), by cations to form sheets. Adjacent meso cations in (3) are related by a 2₁ axis and adjacent chiral cations in (4) are related by a glide plane.

Keywords: Adducts; Supramolecular structures; Racemic.