Crystal structures of three anhydrous salts of the Lewis base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with the ring-substituted benzoic acid analogues 4-aminobenzoic acid, 3,5-dinitrobenzoic acid and 3,5-dinitrosalicylic acid

Abstract

The anhydrous morpholinium salts of 1,8-di­aza­bicyclo­[5.4.0]undec-7-ene (DBU) with 4-amino­benzoic acid, 3,5-di­nitro­benzoic acid and 3,5-di­nitro­salicylic acid, provide one example of a three-dimensional hydrogen-bonded network polymer and two of weakly inter-associated hydrogen-bonded cation–anion units.

A resonance-assisted intramolecular hydrogen bond in compounds containing 2-hydroxy-3,5-dinitrobenzoic acid and its various deprotonated forms: redetermination of several related structures

“…WADXOR (Smith & Lynch, 2016): The non-centrosymmetric structure is composed of light atoms only (the heaviest atoms present in the structure are oxygens) and the data collection was carried out with Mo K radiation. The original article reported the refined Flack parameter to be equal to À0.1 (13); however, the refinement using JANA2006 (Petříček et al, 2014) did not converge and therefore the Flack parameter was set to 0.5 without being refined.…”