2-Amino-5-chloropyridinium salicylate

In the crystal structure of the title salt, C5H6ClN2 +·C7H5O3 −, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms via a pair of N—H⋯O hydrogen bonds, forming R 2 2(8) ring motifs. These motifs are centrosymmetrically paired via N—H⋯O hydrogen bonds, forming a complementary donor–donor–acceptor–acceptor (DDAA) array. A typical intramolecular O—H⋯O hydrogen bond is also observed in the salicylate anion. The crystal structure is further stabilized by weak C—H⋯π interactions.

In the crystal structure of the title salt, C 5 H 6 ClN 2 + ÁC 7 H 5 O 3 À , the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms via a pair of N-HÁ Á ÁO hydrogen bonds, forming R 2 2 (8) ring motifs. These motifs are centrosymmetrically paired via N-HÁ Á ÁO hydrogen bonds, forming a complementary donor-donoracceptor-acceptor (DDAA) array. A typical intramolecular O-HÁ Á ÁO hydrogen bond is also observed in the salicylate anion. The crystal structure is further stabilized by weak C-HÁ Á Á interactions.

D-HÁ
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 Comment 2-Aminopyridine is one of the most frequently used synthons in supramolecular chemistry based on hydrogen bonds (Gellert & Hsu, 1988;Banerjee & Murugavel, 2004;Bis & Zaworotko, 2005;Bis et al., 2006). A series of similar complexes formed from 2-amino-5-chloropyridine and carboxylates has been reported previously (Hemamalini & Fun, 2010a,b,c). Salicylic acid (Cochran, 1953) and its derivatives are widely used as analgesic. They are also used for various gastric tympany and externally as antiseptic and antifungal agents for various skin conditions. The crystal structure of salicylic acid and its complexes, for example, antipyrine-salicylic acid (salipyrine) (Singh & Vijayan, 1974) and piperazinedione-salicylic acid , 1982), have been reported in literature. In a continuation of our studies of pyridinium derivatives, the crystal structure determination of the title compound has been undertaken.

Experimental
A hot methanol solution (20 ml) of 2-amino-5-chloropyridine (64 mg, Aldrich) and salicylic acid (69 mg, Merck) were mixed and warmed over a magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound appeared after a few days.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq