4-Dimethylaminopyridinium picrate: supramolecular aggregation through extensive N—H...O and C—H...O interactions

Abstract

Key indicatorsSingle-crystal X-ray study T = 100 K Mean '(C±C) = 0.003 A Ê R factor = 0.072 wR factor = 0.155 Data-to-parameter ratio = 12.5For details of how these key indicators were automatically derived from the article, see

1-(7-Chloro-1,4-dihydroquinolin-4-ylidene)thiosemicarbazide and its hydrochloride: evidence for the existence of a stable imine tautomer in the solid state of 4-aminoquinoline free bases, an anomalous case in nitrogen heterocycles

“…The bond lengths and angles for similar structures have been published previously, most importantly for (7-chloroquinolin-4-yl)hydrazones (de Souza et al, 2010Souza et al, , 2012 and 4-aminopyridines (Anderson et al, 2005), together with their corresponding pyridinium salts (Smith & Wermuth, 2011;Vembu et al, 2003), which most closely approximate the title compounds. The distinction between free bases and salts is most easily made from comparison of the heterocyclic nitrogen bond angle and the exocyclic N-C bond distance.…”

3-Methylanilinium picrate

“…a specific delocalization around atom C1, and this has been observed in almost all picrate salts. An analysis of related C-O and C-C (C1-C2 or C1-C6) distances among the picrates shows that as the C-O distance increases, the C-C distance decreases (Anitha et al, 2004;Takayanagi et al, 1996;Kaftory et al, 1998;Tanaka et al, 1994;Vembu et al, 2003). Neither of the ortho-nitro groups lies in the benzene plane; while dihedral angle for O2Á Á ÁO3 is 43.9 (1) , the other nitro group has two possible orientations having dihedral angles of 36.6 (2) and 27.0 (4) .…”

Synthesis, Crystal Structure and Infrared Characterization of Bis(4-dimethylamino-pyridinium) Tetrachlorocuprate

“…A pyridinium cation always possesses an expanded C-N-C angle in comparison with the parent pyridine. The angle C 1 -N 1 -C 5 of 120.83 (10)˚ is typical for the protonated forms of dimethylpyridine reported in many structures [34]- [52].…”