Anhydrous 1:1 proton-transfer compounds of isonipecotamide with picric acid and 3,5-dinitrosalicylic acid: 4-carbamoylpiperidinium 2,4,6-trinitrophenolate and two polymorphs of 4-carbamoylpiperidinium 2-carboxy-4,6-dinitrophenolate
Smith, Graham & Wermuth, Urs D. (2010) Anhydrous 1:1 proton-transfer compounds of isonipecotamide with picric acid and 3,5-dinitrosalicylic acid: 4-carbamoylpiperidinium 2,4,6-trinitrophenolate and two polymorphs of 4-carbamoylpiperidinium 2-carboxy-4,6-dinitrophenolate. Acta Crystallographica. Section C: Crystal Structure Communications, 66(12), o609-o613.
The structures of the anhydrous 1:1 proton-transfer compounds of isonipecotamide (4-carbamoylpiperidine) with picric acid and 3,5-dinitrosalicylic acid, namely 4-carbamoylpiperidinium 2,4,6-trinitrophenolate, C6H13N2O8+ C6H2N3O7- (I) and 4-carbamoylpiperidinium 2-carboxy-4,6-dinitrophenolate, C6H13N2O8+ C7H3N2O7-: two forms, the monoclinic alpha-polymorph (II) and the triclinic beta-polymorph (III) have been determined at 200 K. All compounds form hydrogen-bonded structures, one-dimensional in (II), two-dimensional in (I) and three-dimensional in (III). In (I), the cations form centrosymmetric cyclic head-to-tail hydrogen-bonded homodimers [graph set R2/2(14)] through lateral duplex piperidinium N---H...O(amide) interactions. These dimers are extended into a two-dimensional network structure through further interactions with anion phenolate-O and nitro-O acceptors, including a direct symmetric piperidinium N-H...O(phenol),O(nitro) cation--anion association [graph set R2/1(6)]. The monoclinic polymorph (II) has a similar R2/1(6) cation-anion hydrogen-bonding interaction to (I) but with an additional conjoint symmetrical R1/2(4) interaction as well as head-to-tail piperidinium N-H...O(amide) O hydrogen bonds and amide N-H...O(carboxyl) hydrogen bonds, give a network structure which include large R3/4(20) rings. The hydrogen bonding in the triclinic polymorph (III) is markedly different from that of monoclinic (II). The asymmetric unit contains two independent cation-anion pairs which associate through cyclic piperidinium N-H...O,O'(carboxyl) interactions [graph set R2/1(4)]. The cations also show the zig-zag head-to-tail piperidinium N-H...O(amide) hydrogen-bonded chain substructures found in (II) but in addition feature amide N-H...O(nitro) and O(phenolate) and amide N-H...O(nitro) associations. As well there is a centrosymmetric double-amide N-H...O(carboxyl) bridged bis(cation-anion) ring system [graph set R2/4(8)] in the three-dimensional framework. The structures reported here demonstrate the utility of the isonipecotamide cation as a synthon with previously unrecognized potential for structure assembly applications. Furthermore, the structures of the two polymorphic 3,5-dinitrosalicylic acid salts show an unusual dissimilarity in hydrogen-bonding characteristics, considering that both were obtained from identical solvent systems.
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|Item Type:||Journal Article|
|Keywords:||crystal structure, hydrogen bonding, proton transfer, isonipecotamide|
|Subjects:||Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > PHYSICAL CHEMISTRY (INCL. STRUCTURAL) (030600) > Structural Chemistry and Spectroscopy (030606)|
|Divisions:||Past > Schools > Chemistry
Past > QUT Faculties & Divisions > Faculty of Science and Technology
|Copyright Owner:||Copyright 2010 International Union of Crystallography|
|Deposited On:||29 Nov 2010 04:24|
|Last Modified:||29 Feb 2012 14:27|
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