Acta Crystallographica Section C

Volume 67, Part 7 (July 2011)

organic compounds

su3064 scheme

Acta Cryst. (2011). C67, o259-o264 [ doi:10.1107/S0108270111020518 ]

Proton-transfer compounds of isonipecotamide with the aromatic dicarboxylic acids 4-nitrophthalic, 4,5-dichlorophthalic, 5-nitroisophthalic and terephthalic acid

G. Smith and U. D. Wermuth

Abstract: The structures of the 1:1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with 4-nitrophthalic acid [4-carbamoylpiperidinium 2-carboxy-4-nitrobenzoate, C₆H₁₃N₂O₈⁺·C₈H₄O₆^-, (I)], 4,5-dichlorophthalic acid [4-carbamoylpiperidinium 2-carboxy-4,5-dichlorobenzoate, C₆H₁₃N₂O₈⁺·C₈H₃Cl₂O₄^-, (II)] and 5-nitroisophthalic acid [4-carbamoylpiperidinium 3-carboxy-5-nitrobenzoate, C₆H₁₃N₂O₈⁺·C₈H₄O₆^-, (III)], as well as the 2:1 compound with terephthalic acid [bis(4-carbamoylpiperidinium) benzene-1,2-dicarboxylate dihydrate, 2C₆H₁₃N₂O₈⁺·C₈H₄O₄^2-·2H₂O, (IV)], have been determined at 200 K. All salts form hydrogen-bonded structures, viz. one-dimensional in (II) and three-dimensional in (I), (III) and (IV). In (I) and (III), the centrosymmetric R₂²(8) cyclic amide-amide association is found, while in (IV) several different types of water-bridged cyclic associations are present [graph sets R₄²(8), R₄³(10), R₄⁴(12), R₃³(18) and R₆⁴(22)]. The one-dimensional structure of (I) features the common `planar' hydrogen 4,5-dichlorophthalate anion, together with enlarged cyclic R₃³(13) and R₄³(17) associations. In the structures of (I) and (III), the presence of head-to-tail hydrogen phthalate chain substructures is found. In (IV), head-to-tail primary cation-anion associations are extended longitudinally into chains through the water-bridged cation associations, and laterally by piperidinium-carboxylate N-HO and water-carboxylate O-HO hydrogen bonds. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. An additional example of cation-anion association with this cation is also shown in the asymmetric three-centre piperidinium-carboxylate N-HO,O' interaction in the first-reported structure of a 2:1 isonipecotamide-carboxylate salt.

Formula: Two forms of C₆H₁₃N₂O⁺·C₈H₄NO₆^-, and C₆H₁₃N₂O₈⁺·C₈H₃Cl₂O₄^- and 2C₆H₁₃N₂O₈⁺·C₈H₄O₄^2-·2H₂O


	Structure factor file (CIF format) (143.7 kbytes) [ doi:10.1107/S0108270111020518/su3064Isup2.hkl ] Contains datablock I

	Structure factor file (CIF format) (148.3 kbytes) [ doi:10.1107/S0108270111020518/su3064IIsup3.hkl ] Contains datablock II

	Structure factor file (CIF format) (141.4 kbytes) [ doi:10.1107/S0108270111020518/su3064IIIsup4.hkl ] Contains datablock III

	Structure factor file (CIF format) (104.8 kbytes) [ doi:10.1107/S0108270111020518/su3064IVsup5.hkl ] Contains datablock IV

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