In the structure of the 1:1 proton-transfer compound from the reaction of l-tartaric acid with the azo-dye precursor aniline yellow [4-(phenyl - diazenyl)aniline], namely 4-(phenyl-di-az-enyl)-anilinium (2R,3R)-3-carb-oxy-2, 3-dihy-droxy-propano-ate, C12H12N3 +·C4H5O6 -, the asymmetric unit contains two independent 4-(phenyl-diazenyl)-anilinium cations and two hydrogen l-tartrate anions. The structure is unusual in that all four phenyl rings of the two cations have identical rotational disorder with equal occupancy of the conformations. The two hydrogen l-tartrate anions form independent but similar chains through head-to-tail carboxyl-carboxyl-ate O - H⋯O hydrogen bonds [graph set C(7)], which are then extended into a two-dimensional hydrogen-bonded sheet structure through hy-droxy O - H⋯O hydrogen-bonded links. The anilinium groups of the 4-(phenyl-diazenyl)-anilinium cations are incorporated into the sheets and also provide inter-nal hydrogen-bonded extensions, while their aromatic tails are layered in the structure without significant association except for weak π-π inter-actions [minimum ring centroid separation = 3.844 (3) Å]. The hydrogen l-tartrate residues of both anions exhibit the common short intra-molecular hy-droxy-carboxylate O - H⋯O hydogen bonds. This work provides a solution to the unusual disorder problem inherent in the structure of this salt, as well as giving another example of the utility of the hydrogen tartrate anion in the generation of sheet substructures in mol-ecular assembly processes.
|Number of pages||4|
|Journal||Acta Crystallographica Section C: Crystal Structure Communications|
|Issue number||Part 7|
|Publication status||Published - 16 Jul 2010|