organic compounds
of 2-aminopyridinium 6-chloronicotinate
aSchool of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India, and bSchool of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: tommtrichy@yahoo.co.in
In the title salt, C5H7N+·C6H3ClNO−, the 2-aminopyridinium cation interacts with the carboxylate group of the 6-chloronicotinate anion through a pair of independent N—H⋯O hydrogen bonds, forming an R22(8) ring motif. In the crystal, these dimeric units are connected further via N—H⋯O hydrogen bonds, forming chains along [001]. In addition, weak C—H⋯N and C—H⋯O hydrogen bonds, together with weak π–π interactions, with centroid–centroid distances of 3.6560 (5) and 3.6295 (5) Å, connect the chains, forming a two-dimensional network parallel to (100).
Keywords: crystal structure; 2-aminopyridinium; 6-chloronicotinate; 6-chloropyridine-3-carboxylate; noncovalent interactions; π–π stacking interactions.
CCDC reference: 1417413
1. Related literature
For a background to noncovalent interactions, see: García-Raso et al. (2009). For the applications of pyridine compounds, see: Schwid et al. (1997); Rajkumar et al. (2015). For related structures, see: Xie (2007); Jennifer & Muthiah (2014); Chao et al. (1975); Bis & Zaworotko (2005); Jebas & Balasubramanian (2006). For information on π–π stacking interactions, see: Hunter (1994). For hydrogen-bond graph-set motifs, see: Bernstein et al. (1995);
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: APEX2 (Bruker, 2009); cell SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: PLATON.
Supporting information
CCDC reference: 1417413
https://doi.org/10.1107/S2056989015014796/lh5778sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989015014796/lh5778Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989015014796/lh5778Isup3.cml
A hot ethanolic solution of 2-aminopyridine (23 mg, Aldrich) and 6-chloronicotinic acid (39 mg, Alfa Aesar) was warmed for half an hour over a water bath. The mixture was cooled slowly and kept at room temperature. After a few days colourless plate like crystals were obtained.
Hydrogen atoms boned to C atoms were place in calculated postions with with C—H = 0.95Å and included with Uiso(H) = 1.2Ueq(C). H atoms boned to N atoms were refined independently with isotropic displacement parameters.
Noncovalent interactions such as hydrogen bonding, anion-π, cation-π, and π-π interactions, and other weak forces play a central role in many areas. They are very important in deciding the conformation of molecules, chemical reactions, molecular recognition, regulating biochemical processes and governing the organization of multicomponent supramolecular assemblies (García-Raso et al., 2009). 2-Aminopyridines are used in the manufacture of pharmaceutical drugs, especially for the treatment of neurological ailments (Schwid et al., 1997). Pyridine heterocycles and their derivatives have large applications in the field of photo-chemical, electrochemical and catalytic process. Some pyridine derivatives possess non-linear optical (NLO) properties (Rajkumar et al., 2015). The of 2-aminopyridinium isonicotinate 2-aminopyridine has already been reported (Xie, 2007). The salts of aminopyridine-thiophenecarboxylic acid (Jennifer & Muthiah, 2014) have been recently reported from our laboratory. We report herein the of the title molecular salt, obtained by the reaction of 2-aminopyridine with 6-chloronicotinic acid.
The π–π stacking interactions involving the 6-chloronicotinate and pyridinium ions. A Cg1-Cg2 distance of 3.6560 (5) Å and Cg2—Cg2 distance of 3.6295 (5) Å is observed (where Cg1 is the centroid of the N1/C1-C5 ring and Cg2 is the centroid of the N2/C7-C11 ring). The perpendicular distances of 3.2545 (3) and 3.5411 (3)Å together with the slip angles of 22.3 & 12.7°, respectively are typical for aromatic stacking values (Hunter, 1994).
of the title salt, (I), contains one 2-aminopyridinium cation and a 6-chloronicotinate anion (Fig. 1). Protonation of the cation occurs at N2, providing a C7—N2—C11 angle of 122.45 (7)° compared with 117.7 (1)° in the unprotonated 2-aminopyridine (Chao et al., 1975). A similar type of protonation is observed in various 2-aminopyridine acid complexes (Bis & Zaworotko, 2005). The bond lengths and angles in complex (I) are within normal ranges and comparable to those in other 2-aminopyridinium complexes (Jebas & Balasubramanian, 2006). The carboxylate group of the 6-chloronicotinate anion interacts with the protonated atom N2 and the amino group of the pyridine moiety through a pair of N—H···O hydrogen bonds, forming an eight membered R22(8) ring motif (Bernstein et al., 1995). Furthermore, these motifs are connected via N3—H1···O2ii, C7—H7A···N1iii and C10—H10A···O1iv hydrogen bonds (see Table 1 for symmetry codes), forming a two-dimensional network parallel to (100) (Fig 2). The is further stabilized by two distinctFor a background to noncovalent interactions, see: García-Raso et al. (2009). For the applications of pyridine compounds, see: Schwid et al. (1997); Rajkumar et al. (2015). For related structures, see: Xie (2007); Jennifer & Muthiah (2014); Chao et al. (1975); Bis & Zaworotko (2005); Jebas & Balasubramanian (2006). For information on π–π stacking interactions, see: Hunter (1994). For hydrogen-bond graph-set motifs, see: Bernstein et al. (1995);
Data collection: APEX2 (Bruker, 2009); cell
SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: PLATON (Spek, 2009).Fig. 1. The asymmetric unit of the title compound, showing 30% probability displacement ellipsoids. | |
Fig. 2. Part of the crystal structure with hydrogen bonds shown as dashed lines. Hydrogen atoms not involved hydrogen bonding have been removed for clarity. |
C5H7N2+·C6H3ClNO2− | Z = 4 |
Mr = 251.67 | F(000) = 520 |
Monoclinic, P21/c | Dx = 1.499 Mg m−3 |
Hall symbol: -P 2ybc | Mo Kα radiation, λ = 0.71073 Å |
a = 8.6844 (4) Å | θ = 2.4–32.7° |
b = 10.8112 (5) Å | µ = 0.34 mm−1 |
c = 11.9235 (6) Å | T = 100 K |
β = 95.2046 (9)° | Plate, colourless |
V = 1114.87 (9) Å3 | 0.51 × 0.40 × 0.17 mm |
Bruker SMART APEXII DUO CCD area-detector diffractometer | 4073 independent reflections |
Radiation source: fine-focus sealed tube | 3771 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.019 |
φ and ω scans | θmax = 32.7°, θmin = 2.4° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −13→13 |
Tmin = 0.993, Tmax = 0.994 | k = −16→16 |
15546 measured reflections | l = −18→18 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.092 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | W = 1/[Σ2(FO2) + (0.0539P)2 + 0.2679P] where P = (FO2 + 2FC2)/3 |
4073 reflections | (Δ/σ)max < 0.001 |
166 parameters | Δρmax = 0.50 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
C5H7N2+·C6H3ClNO2− | V = 1114.87 (9) Å3 |
Mr = 251.67 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.6844 (4) Å | µ = 0.34 mm−1 |
b = 10.8112 (5) Å | T = 100 K |
c = 11.9235 (6) Å | 0.51 × 0.40 × 0.17 mm |
β = 95.2046 (9)° |
Bruker SMART APEXII DUO CCD area-detector diffractometer | 4073 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 3771 reflections with I > 2σ(I) |
Tmin = 0.993, Tmax = 0.994 | Rint = 0.019 |
15546 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.092 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.50 e Å−3 |
4073 reflections | Δρmin = −0.22 e Å−3 |
166 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
N2 | 0.08234 (8) | 0.17345 (6) | 0.03387 (6) | 0.0142 (2) | |
N3 | −0.02920 (9) | 0.19691 (7) | 0.20096 (6) | 0.0184 (2) | |
C7 | 0.17904 (9) | 0.11677 (8) | −0.03367 (7) | 0.0177 (2) | |
C8 | 0.26497 (11) | 0.01655 (9) | 0.00290 (8) | 0.0228 (2) | |
C9 | 0.25206 (11) | −0.02551 (8) | 0.11385 (8) | 0.0238 (2) | |
C10 | 0.15609 (10) | 0.03247 (8) | 0.18212 (7) | 0.0197 (2) | |
C11 | 0.06759 (9) | 0.13562 (7) | 0.14076 (6) | 0.0146 (2) | |
Cl1 | 0.54962 (2) | 0.18137 (2) | 0.23646 (2) | 0.0203 (1) | |
O1 | 0.18876 (7) | 0.61122 (6) | −0.08641 (5) | 0.0192 (2) | |
O2 | 0.07082 (7) | 0.63585 (6) | 0.07132 (5) | 0.0171 (2) | |
N1 | 0.33406 (8) | 0.35025 (7) | 0.22723 (6) | 0.0166 (2) | |
C1 | 0.43180 (9) | 0.29272 (7) | 0.16629 (7) | 0.0150 (2) | |
C2 | 0.44779 (9) | 0.31497 (8) | 0.05297 (7) | 0.0168 (2) | |
C3 | 0.35703 (9) | 0.40792 (8) | 0.00135 (6) | 0.0158 (2) | |
C4 | 0.25507 (8) | 0.47360 (7) | 0.06340 (6) | 0.0129 (2) | |
C5 | 0.24641 (9) | 0.43930 (7) | 0.17505 (6) | 0.0152 (2) | |
C6 | 0.16403 (8) | 0.58120 (7) | 0.01150 (6) | 0.0135 (2) | |
H1N2 | 0.0255 (18) | 0.2389 (16) | 0.0024 (14) | 0.038 (4)* | |
H2N3 | −0.0831 (18) | 0.2538 (16) | 0.1688 (13) | 0.032 (4)* | |
H1N3 | −0.0454 (17) | 0.1728 (14) | 0.2703 (13) | 0.031 (4)* | |
H7A | 0.18690 | 0.14750 | −0.10760 | 0.0210* | |
H8A | 0.33130 | −0.02370 | −0.04470 | 0.0270* | |
H9A | 0.31080 | −0.09500 | 0.14140 | 0.0290* | |
H10A | 0.14880 | 0.00380 | 0.25680 | 0.0240* | |
H2A | 0.51770 | 0.26860 | 0.01280 | 0.0200* | |
H3A | 0.36410 | 0.42690 | −0.07580 | 0.0190* | |
H5A | 0.17440 | 0.48120 | 0.21690 | 0.0180* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N2 | 0.0166 (3) | 0.0150 (3) | 0.0112 (3) | −0.0003 (2) | 0.0027 (2) | 0.0014 (2) |
N3 | 0.0217 (3) | 0.0218 (3) | 0.0125 (3) | 0.0003 (3) | 0.0053 (2) | 0.0033 (2) |
C7 | 0.0201 (3) | 0.0187 (3) | 0.0148 (3) | −0.0004 (3) | 0.0040 (3) | −0.0023 (3) |
C8 | 0.0229 (4) | 0.0206 (4) | 0.0249 (4) | 0.0039 (3) | 0.0024 (3) | −0.0044 (3) |
C9 | 0.0256 (4) | 0.0174 (4) | 0.0274 (4) | 0.0034 (3) | −0.0034 (3) | 0.0010 (3) |
C10 | 0.0234 (3) | 0.0170 (3) | 0.0180 (3) | −0.0014 (3) | −0.0024 (3) | 0.0050 (3) |
C11 | 0.0166 (3) | 0.0150 (3) | 0.0121 (3) | −0.0037 (2) | 0.0007 (2) | 0.0017 (2) |
Cl1 | 0.0195 (1) | 0.0189 (1) | 0.0224 (1) | 0.0050 (1) | 0.0020 (1) | 0.0033 (1) |
O1 | 0.0249 (3) | 0.0212 (3) | 0.0123 (2) | 0.0042 (2) | 0.0063 (2) | 0.0025 (2) |
O2 | 0.0212 (3) | 0.0187 (3) | 0.0119 (2) | 0.0056 (2) | 0.0047 (2) | 0.0000 (2) |
N1 | 0.0196 (3) | 0.0161 (3) | 0.0145 (3) | 0.0028 (2) | 0.0036 (2) | 0.0008 (2) |
C1 | 0.0144 (3) | 0.0138 (3) | 0.0167 (3) | 0.0005 (2) | 0.0016 (2) | 0.0004 (2) |
C2 | 0.0164 (3) | 0.0175 (3) | 0.0173 (3) | 0.0017 (2) | 0.0060 (3) | −0.0007 (2) |
C3 | 0.0172 (3) | 0.0171 (3) | 0.0136 (3) | 0.0004 (3) | 0.0050 (2) | −0.0005 (2) |
C4 | 0.0140 (3) | 0.0130 (3) | 0.0119 (3) | −0.0008 (2) | 0.0025 (2) | −0.0007 (2) |
C5 | 0.0182 (3) | 0.0150 (3) | 0.0129 (3) | 0.0021 (3) | 0.0043 (2) | 0.0000 (2) |
C6 | 0.0151 (3) | 0.0142 (3) | 0.0112 (3) | −0.0008 (2) | 0.0019 (2) | −0.0008 (2) |
Cl1—C1 | 1.7438 (8) | C10—C11 | 1.4173 (12) |
O1—C6 | 1.2489 (9) | C7—H7A | 0.9500 |
O2—C6 | 1.2719 (9) | C8—H8A | 0.9500 |
N2—C11 | 1.3556 (10) | C9—H9A | 0.9500 |
N2—C7 | 1.3609 (11) | C10—H10A | 0.9500 |
N3—C11 | 1.3305 (11) | C1—C2 | 1.3917 (12) |
N2—H1N2 | 0.923 (17) | C2—C3 | 1.3863 (12) |
N3—H2N3 | 0.844 (16) | C3—C4 | 1.3980 (11) |
N3—H1N3 | 0.890 (15) | C4—C5 | 1.3905 (10) |
N1—C5 | 1.3444 (11) | C4—C6 | 1.5075 (10) |
N1—C1 | 1.3218 (11) | C2—H2A | 0.9500 |
C7—C8 | 1.3645 (13) | C3—H3A | 0.9500 |
C8—C9 | 1.4129 (13) | C5—H5A | 0.9500 |
C9—C10 | 1.3687 (13) | ||
Cl1···C4i | 3.5893 (8) | C6···N2v | 3.4200 (10) |
Cl1···C5i | 3.2804 (8) | C6···O2v | 3.2056 (10) |
Cl1···C9 | 3.6238 (10) | C7···C3 | 3.5149 (12) |
Cl1···H8Aii | 3.1000 | C7···C2 | 3.2663 (12) |
Cl1···H3Aiii | 3.1000 | C7···N1vii | 3.2808 (11) |
Cl1···H9Aiv | 3.0200 | C9···Cl1 | 3.6238 (10) |
O1···N3v | 2.7830 (10) | C10···O1iii | 3.1574 (10) |
O1···C2vi | 3.2450 (10) | C11···C1 | 3.5787 (11) |
O1···C10vii | 3.1574 (10) | C11···N1 | 3.3719 (11) |
O2···C6v | 3.2056 (10) | C3···H3Avi | 3.0700 |
O2···C4v | 3.3415 (10) | C5···H7Aiii | 2.8500 |
O2···N3viii | 2.8490 (9) | C6···H1N3viii | 3.049 (15) |
O2···N2v | 2.7000 (9) | C6···H1N2v | 2.544 (17) |
O1···H3A | 2.5000 | C6···H2N3v | 2.833 (16) |
O1···H1N2v | 2.726 (16) | H1N2···H2N3 | 2.28 (2) |
O1···H10Avii | 2.2500 | H1N2···O1v | 2.726 (16) |
O1···H2N3v | 1.942 (17) | H1N2···O2v | 1.781 (17) |
O2···H5A | 2.5200 | H1N2···C6v | 2.544 (17) |
O2···H1N2v | 1.781 (17) | H2N3···O1v | 1.942 (17) |
O2···H1N3viii | 1.962 (15) | H2N3···C6v | 2.833 (16) |
N1···C11 | 3.3719 (11) | H2N3···H1N2 | 2.28 (2) |
N1···C7iii | 3.2808 (11) | H1N3···C6ix | 3.049 (15) |
N2···O2v | 2.7000 (9) | H1N3···H10A | 2.5000 |
N2···C6v | 3.4200 (10) | H1N3···O2ix | 1.962 (15) |
N3···O1v | 2.7830 (10) | H1N3···H5Aix | 2.3700 |
N3···O2ix | 2.8490 (9) | H3A···O1 | 2.5000 |
N1···H7Aiii | 2.4400 | H3A···C3vi | 3.0700 |
N3···H5Aix | 2.8700 | H3A···Cl1vii | 3.1000 |
C1···C11 | 3.5787 (11) | H5A···O2 | 2.5200 |
C2···C3vi | 3.5309 (12) | H5A···N3viii | 2.8700 |
C2···C7 | 3.2663 (12) | H5A···H1N3viii | 2.3700 |
C2···O1vi | 3.2450 (10) | H5A···H7Aiii | 2.5100 |
C3···C3vi | 3.1853 (12) | H7A···H5Avii | 2.5100 |
C3···C7 | 3.5149 (12) | H7A···N1vii | 2.4400 |
C3···C2vi | 3.5309 (12) | H7A···C5vii | 2.8500 |
C4···Cl1iv | 3.5893 (8) | H8A···Cl1ii | 3.1000 |
C4···O2v | 3.3415 (10) | H9A···Cl1i | 3.0200 |
C5···Cl1iv | 3.2804 (8) | H10A···O1iii | 2.2500 |
C6···C6v | 3.3366 (10) | H10A···H1N3 | 2.5000 |
C7—N2—C11 | 122.45 (7) | C9—C10—H10A | 120.00 |
C7—N2—H1N2 | 116.2 (10) | C11—C10—H10A | 120.00 |
C11—N2—H1N2 | 121.4 (10) | Cl1—C1—N1 | 116.05 (6) |
C11—N3—H2N3 | 118.0 (11) | Cl1—C1—C2 | 118.64 (6) |
C11—N3—H1N3 | 121.1 (10) | N1—C1—C2 | 125.31 (7) |
H2N3—N3—H1N3 | 120.5 (14) | C1—C2—C3 | 116.97 (7) |
C1—N1—C5 | 116.58 (7) | C2—C3—C4 | 119.68 (7) |
N2—C7—C8 | 121.16 (8) | C3—C4—C5 | 117.59 (7) |
C7—C8—C9 | 117.85 (8) | C3—C4—C6 | 120.56 (6) |
C8—C9—C10 | 120.92 (8) | C5—C4—C6 | 121.80 (6) |
C9—C10—C11 | 119.58 (8) | N1—C5—C4 | 123.81 (7) |
N3—C11—C10 | 123.60 (7) | O1—C6—O2 | 125.14 (7) |
N2—C11—N3 | 118.37 (7) | O1—C6—C4 | 117.13 (6) |
N2—C11—C10 | 118.04 (7) | O2—C6—C4 | 117.71 (6) |
N2—C7—H7A | 119.00 | C1—C2—H2A | 122.00 |
C8—C7—H7A | 119.00 | C3—C2—H2A | 121.00 |
C9—C8—H8A | 121.00 | C2—C3—H3A | 120.00 |
C7—C8—H8A | 121.00 | C4—C3—H3A | 120.00 |
C8—C9—H9A | 120.00 | N1—C5—H5A | 118.00 |
C10—C9—H9A | 120.00 | C4—C5—H5A | 118.00 |
C11—N2—C7—C8 | 1.11 (12) | Cl1—C1—C2—C3 | −177.22 (6) |
C7—N2—C11—N3 | 179.67 (8) | N1—C1—C2—C3 | 2.22 (13) |
C7—N2—C11—C10 | −0.50 (11) | C1—C2—C3—C4 | −0.29 (12) |
C1—N1—C5—C4 | −0.78 (12) | C2—C3—C4—C5 | −1.86 (11) |
C5—N1—C1—Cl1 | 177.76 (6) | C2—C3—C4—C6 | 175.44 (7) |
C5—N1—C1—C2 | −1.69 (12) | C3—C4—C5—N1 | 2.51 (12) |
N2—C7—C8—C9 | −0.90 (13) | C6—C4—C5—N1 | −174.75 (7) |
C7—C8—C9—C10 | 0.14 (14) | C3—C4—C6—O1 | −2.82 (11) |
C8—C9—C10—C11 | 0.44 (13) | C3—C4—C6—O2 | 178.64 (7) |
C9—C10—C11—N2 | −0.26 (12) | C5—C4—C6—O1 | 174.36 (7) |
C9—C10—C11—N3 | 179.55 (8) | C5—C4—C6—O2 | −4.18 (11) |
Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) −x+1, −y, −z; (iii) x, −y+1/2, z+1/2; (iv) −x+1, y+1/2, −z+1/2; (v) −x, −y+1, −z; (vi) −x+1, −y+1, −z; (vii) x, −y+1/2, z−1/2; (viii) −x, y+1/2, −z+1/2; (ix) −x, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H1N2···O2v | 0.923 (17) | 1.781 (17) | 2.7000 (9) | 173.5 (15) |
N3—H2N3···O1v | 0.844 (16) | 1.942 (17) | 2.7830 (10) | 174.1 (15) |
N3—H1N3···O2ix | 0.890 (15) | 1.962 (15) | 2.8490 (9) | 174.0 (13) |
C7—H7A···N1vii | 0.95 | 2.44 | 3.2808 (11) | 147 |
C10—H10A···O1iii | 0.95 | 2.25 | 3.1574 (10) | 160 |
Symmetry codes: (iii) x, −y+1/2, z+1/2; (v) −x, −y+1, −z; (vii) x, −y+1/2, z−1/2; (ix) −x, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H1N2···O2i | 0.923 (17) | 1.781 (17) | 2.7000 (9) | 173.5 (15) |
N3—H2N3···O1i | 0.844 (16) | 1.942 (17) | 2.7830 (10) | 174.1 (15) |
N3—H1N3···O2ii | 0.890 (15) | 1.962 (15) | 2.8490 (9) | 174.0 (13) |
C7—H7A···N1iii | 0.95 | 2.44 | 3.2808 (11) | 147 |
C10—H10A···O1iv | 0.95 | 2.25 | 3.1574 (10) | 160 |
Symmetry codes: (i) −x, −y+1, −z; (ii) −x, y−1/2, −z+1/2; (iii) x, −y+1/2, z−1/2; (iv) x, −y+1/2, z+1/2. |
Acknowledgements
NJJ thanks the UGC–SAP, India, for the award of an RFSMS. PTM is thankful to the UGC, New Delhi, for a UGC–BSR one-time grant to Faculty. IAR and MMR thank the Malaysian Government and Universiti Sains Malaysia (USM) for the research facilities to conduct this work.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Noncovalent interactions such as hydrogen bonding, anion-π, cation-π, and π-π interactions, and other weak forces play a central role in many areas. They are very important in deciding the conformation of molecules, chemical reactions, molecular recognition, regulating biochemical processes and governing the organization of multicomponent supramolecular assemblies (García-Raso et al., 2009). 2-Aminopyridines are used in the manufacture of pharmaceutical drugs, especially for the treatment of neurological ailments (Schwid et al., 1997). Pyridine heterocycles and their derivatives have large applications in the field of photo-chemical, electrochemical and catalytic process. Some pyridine derivatives possess non-linear optical (NLO) properties (Rajkumar et al., 2015). The crystal structure of 2-aminopyridinium isonicotinate 2-aminopyridine has already been reported (Xie, 2007). The salts of aminopyridine-thiophenecarboxylic acid (Jennifer & Muthiah, 2014) have been recently reported from our laboratory. We report herein the crystal structure of the title molecular salt, obtained by the reaction of 2-aminopyridine with 6-chloronicotinic acid.
The asymmetric unit of the title salt, (I), contains one 2-aminopyridinium cation and a 6-chloronicotinate anion (Fig. 1). Protonation of the cation occurs at N2, providing a C7—N2—C11 angle of 122.45 (7)° compared with 117.7 (1)° in the unprotonated 2-aminopyridine (Chao et al., 1975). A similar type of protonation is observed in various 2-aminopyridine acid complexes (Bis & Zaworotko, 2005). The bond lengths and angles in complex (I) are within normal ranges and comparable to those in other 2-aminopyridinium complexes (Jebas & Balasubramanian, 2006). The carboxylate group of the 6-chloronicotinate anion interacts with the protonated atom N2 and the amino group of the pyridine moiety through a pair of N—H···O hydrogen bonds, forming an eight membered R22(8) ring motif (Bernstein et al., 1995). Furthermore, these motifs are connected via N3—H1···O2ii, C7—H7A···N1iii and C10—H10A···O1iv hydrogen bonds (see Table 1 for symmetry codes), forming a two-dimensional network parallel to (100) (Fig 2). The crystal structure is further stabilized by two distinct π–π stacking interactions involving the 6-chloronicotinate and pyridinium ions. A Cg1-Cg2 distance of 3.6560 (5) Å and Cg2—Cg2 distance of 3.6295 (5) Å is observed (where Cg1 is the centroid of the N1/C1-C5 ring and Cg2 is the centroid of the N2/C7-C11 ring). The perpendicular distances of 3.2545 (3) and 3.5411 (3)Å together with the slip angles of 22.3 & 12.7°, respectively are typical for aromatic stacking values (Hunter, 1994).