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The crystal structures of three proton-transfer compounds of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with 4-X-substituted anilines (X = F, Cl and Br), namely 4-fluoroanilinium 5-sulfosalicylate (3-carboxy-4-hydroxyben- zenesulfonate) monohydrate, C6H7FN+·C7H5O6S¯·H2O, (I), 4-chloroanilinium 5-sulfosalicylate hemihydrate, C6H7C1-N+C7H5O6S¯0.5H2O, (II), and 4-bromoanilinium 5-sulfo-salicylate monohydrate, C6H7BrN+·C7H5O6S¯·H2O, (III), have been determined. The asymmetric unit in (II) contains two formula units. All three compounds have three-dimensional hydrogen-bonded polymeric structures in which both the water molecule and the carboxylic acid group are involved in structure extension. With both (II) and (III), which are structurally similar, the common cyclic R²2(8) dimeric carboxylic acid association is present, whereas in (I), an unusual cyclic R³3(8) association involving all three hetero- species is found. [ABSTRACT FROM AUTHOR]

The stereochemistry of the title compound, C19H21N3, has been confirmed by a single-crystal X-ray analysis. The bicyclic ring system adopts a cis-deca­lin-like conformation, which presumably minimizes steric repulsion involving the bridgehead phenyl substituent. The conformation of the amino group appears to be dictated by a nitro­gen anomeric effect. [ABSTRACT FROM AUTHOR]

In the structure of the hydrated 1:1 compound of 4-chloroaniline withl-tartaric acid, C6H7ClN+·C4H5O6−·H2O, determined at 130 K, the asymmetric unit comprises two 4-chloroanilinium cations, two hydrogen tartrate anions and two water molecules of solvation, and forms a two-dimensional duplex substructure comprising head-to-tail C11(7) hydrogen-bonded hydrogen tartrate anions and water molecules. The π-associated 4-chloroanilinium cation pairs [ring centroid separation = 3.576 (4) Å; inter-ring dihedral angle = 0.5 (1)°] are accommodated within the channels of the substructure and are hydrogen-bonded to it peripherally. [ABSTRACT FROM AUTHOR]

In the title compound, C9H8N+·C6H7O7−, the dihydrogen citrate anions form a convoluted two-dimensional hydrogen-bonded substructure through head-to-tail interactions with the interstitial π-stacked quinolinium cations linked to it peripherally through cyclic R12(5) N+—H...O(carboxyl/hydroxyl) hydrogen-bond interactions. The loss of a proton from one of the β-carboxylic acid groups of the citric acid generates a chiral centre in the anion, but these form a racemate in the centrosymmetric crystal structure. [ABSTRACT FROM AUTHOR]

The low-temperature (130 K) structure of the 1:1 proton-transfer compound of brucine with toluene-4-sulfonic acid (systematic name: 2,3-dimeth­oxy-10-oxostrychnidinium toluene-4-sulfonate trihydrate), C23H27N2O4+·C7H7O3S−·3H2O, has been determined. The asymmetric unit contains two cations, two anions and six molecules of water. Brucinium cations form the familiar undulating head-to-tail ribbon structures, which associate with the toluene-4-sulfonate anions and the water mol­ecules in the inter­stitial cavities through hydrogen-bonding associations involving all available donor and acceptor atoms on all species. The result is a framework polymer structure. [ABSTRACT FROM AUTHOR]

The crystal structure of a non-centrosymmetric polymorphic modification of the title compound, C9H7NO4, determined at 130 K, shows the presence of 21 screw-generated one-dimensional zigzag chains formed through catemeric C(4) syn– anti carboxylic acid hydrogen-bonding associations. [ABSTRACT FROM AUTHOR]

The structure of the title, compound C23H27N2O4+·C8H5O4−·3H2O, has been determined at 130 K. The hydrogen isophthalate anions and the water mol­ecules (one of which is disordered over two approximately equal sites) associate through extensive hydrogen-bonded inter­actions, including those with the common undulating brucinium cation layer substructures, forming a three-dimensional framework structure. [ABSTRACT FROM AUTHOR]