Lamellar aggregation and hydrogen-bonding motifs in 3-(aminocarbonyl)pyridinium perchlorate and hydrogen oxalate.

In the title compounds, C(6)H(7)N(2)O(+).ClO(4)(-), (I), and C(6)H(7)N(2)O(+).C(2)HO(4)(-), (II), the carboxamide plane is twisted from the plane of the protonated pyridine ring. Lamellar or sheet-like structural features are observed through N-H...O and O-H...O hydrogen-bonded motifs of cations and anions in (I) and (II), respectively. These sheets are aggregated through C(4) and C(5) chain motifs in (I) and (II), respectively. R(1)(2)(4) ring motifs in (I) and R(1)(2)(5) motifs in (II) are formed via pyridine-anion bifurcated N-H...O interactions. In (II), carboxamide groups form N-H...O dimers around the inversion centres of the unit cell, with R(2)(2)(8) ring motifs. A 2(1) screw-related helical or ribbon-like structure along the b axis is formed in (II) through carboxamide and pyridinium N-H...O hydrogen bonds with the oxalate anions.