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

作者：Smith Graham^*; Wermuth Urs D

来源：Acta Crystallographica Section C-Crystal Structure Communications, 2010, 66: O609-O613.

DOI：10.1107/S010827011004672X

The structures of the anhydrous 1:1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with picric acid and 3,5-dinitrosalicylic acid, namely 4-carbamoylpiperidinium 2,4,6-trinitrophenolate, C6H13N2O+center dot C6H2N3O7-, (I), and 4-carbamoylpiperidinium 2-carboxy-4,6-dinitrophenolate [two forms of which were found, the monoclinic alpha-polymorph, (II), and the triclinic beta-polymorph, (III)], C6H13N2O+center dot C7H3N2O7-, have been determined at 200 K. All three compounds form hydrogen-bonded structures, viz. 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 R-2(2)(14)] through lateral duplex piperidinium-amide N-H center dot center dot center dot O interactions. These dimers are extended into a two-dimensional network structure through further interactions with phenolate and nitro O-atom acceptors, including a direct symmetric piperidinium-phenol/nitro N-H center dot center dot center dot O, O cation-anion association [graph set R-1(2)(6)]. The monoclinic polymorph, (II), has a similar R-1(2)(6) cation-anion hydrogenbonding interaction to (I) but with an additional conjoint symmetrical R-1(2)(4) interaction as well as head-to-tail piperidinium- amide N-H center dot center dot center dot O, O hydrogen bonds and amidecarboxyl N-H center dot center dot center dot O hydrogen bonds, giving a network structure which includes large R-4(3)(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-carboxyl N-H center dot center dot center dot O, O ' interactions [graph set R-1(2)(4)]. The cations also show the zigzag head-to-tail piperidinium-amide N-H center dot center dot center dot O hydrogen-bonded chain sub-structures found in (II), but in addition feature amide-nitro and amide-phenolate N-H center dot center dot center dot O associations. As well, there is a centrosymmetric double-amide N-H center dot center dot center dot Ocarboxyl bridged bis(cation-anion) ring system [graph set R-4(2)(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.

• 出版日期2010-12