Acta Crystallographica Section C

Crystal Structure Communications

Volume 69, Part 10 (October 2013)

organic compounds

Acta Cryst. (2013). C69, 1192-1195    [ doi:10.1107/S010827011302430X ]

Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the di­carb­oxy­lic oxalic and adipic acid homologues

G. Smith and U. D. Wermuth

Abstract: The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O+·C2HO4-·2H2O, (I), and with adipic acid, bis­(4-car­bam­oylpiperidinium) adipate dihydrate, 2C6H13N2O+·C6H8O42-·2H2O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carb­oxy­lic acid O-H...Ocarboxyl hydrogen-bonding inter­actions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N-H...O hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N-H...Ocarboxyl hydrogen bonds, generating cyclic R43(10) and R32(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water mol­ecule. In the crystal structure, the two inversion-related cations are inter­linked through the two water mol­ecules, which act as acceptors in dual amide N-H...Owater hydrogen bonds, to give a cyclic R42(8) association which is conjoined with an R44(12) motif. Further N-H...Owater, water O-H...Oamide and piperidinium N-H...Ocarbox­yl hydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water mol­ecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide-amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

Formula: C6H13N2O+·C2HO4-·2H2O and 2C6H13N2O+·C6H8O4-·2H2O

Keywords: crystal structure; hydrated proton-transfer salts; isonipecotamide salts; cyclic hydrogen-bonding motifs.

hkldisplay filedownload file

Structure factor file (CIF format) (116.4 kbytes)
[ doi:10.1107/S010827011302430X/cu3038Isup2.hkl ]
Contains datablock I

hkldisplay filedownload file

Structure factor file (CIF format) (108.3 kbytes)
[ doi:10.1107/S010827011302430X/cu3038IIsup3.hkl ]
Contains datablock II


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