2-Amino-4,6-dimethyl­pyridinium benzoate

Abstract

In the title compound, C7H11N2⁺·C7H5O2⁻, the 2-amino-4,6-dimethyl­pyridinium cation and the benzoate anion are linked by two N—H⋯O hydrogen bonds, forming an R2²(8) ring motif. The H atoms in both the methyl groups are rotationally disordered, with fixed site occupancies of 0.50. In the crystal structure, the mol­ecules are stabilized by inter­molecular N—H⋯O hydrogen bonds. A π–π inter­action, with a centroid–centroid distance of 3.661 (2) Å, is also observed.

Full text

2-Amino-4,6-dimethylpyridinium
benzoate
Mohd Razip Asaruddin,
a
Habibah A Wahab,
b
‡ Nornisah
Mohamed,
a
Mohd Mustaqim Rosli
c
and Hoong-Kun
Fun
c
*§
a
Pharmaceutical Design and Simulation Laboratory, School of Pharmaceutical
Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia,
b
Institute of
Pharmaceutical and Neutraceuticals, Malaysia Ministry of Science and Technology
and Innovation, Science Complex, 11900, Malaysia, and
c
X-ray Crystallography
Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
Correspondence e-mail: hkfun@usm.my
Received 17 August 2010; accepted 29 August 2010
Key indicators: single-crystal X-ray study; T= 296 K; mean (C–C) = 0.003 A
˚;
Rfactor = 0.044; wR factor = 0.127; data-to-parameter ratio = 11.7.
In the title compound, C
7
H
11
N
2+
C
7
H
5
O
2

, the 2-amino-4,6-
dimethylpyridinium cation and the benzoate anion are linked
by two N—HO hydrogen bonds, forming an R
2
2
(8) ring
motif. The H atoms in both the methyl groups are rotationally
disordered, with fixed site occupancies of 0.50. In the crystal
structure, the molecules are stabilized by intermolecular N—
HO hydrogen bonds. A –interaction, with a centroid–
centroid distance of 3.661 (2) A
˚, is also observed.
Related literature
For the biological activity of Schiff bases with azomethine
linkages, see Dhar & Taploo (1982). For hydrogen bonding,
see: Jeffrey (1997); Jeffrey & Saenger (1991). For graph-set
descriptions of hydrogen-bond ring motifs, see: Bernstein et al.
(1995).
Experimental
Crystal data
C
7
H
11
N
2+
C
7
H
5
O
2

M
r
= 244.29
Monoclinic, P21=c
a= 7.5362 (16) A
˚
b= 22.937 (4) A
˚
c= 8.2124 (14) A
˚
= 109.820 (2)
V= 1335.5 (4) A
˚
3
Z=4
Mo Kradiation
= 0.08 mm
1
T= 296 K
0.57 0.23 0.05 mm
Data collection
Bruker SMART APEXII CCD
area-detector diffractometer
Absorption correction: multi-scan
(SADABS;p Bruker, 2009)
T
min
= 0.954, T
max
= 0.996
7639 measured reflections
2336 independent reflections
1527 reflections with I>2(I)
R
int
= 0.029
Refinement
R[F
2
>2(F
2
)] = 0.044
wR(F
2
) = 0.127
S= 1.02
2336 reflections
199 parameters
H atoms treated by a mixture of
independent and constrained
refinement

max
= 0.10 e A
˚
3

min
=0.14 e A
˚
3
Table 1
Hydrogen-bond geometry (A
˚,).
D—HAD—H HADAD—HA
N1—H1N1O2 1.04 1.65 2.683 (2) 172
N2—H1N2O1 1.01 1.78 2.779 (2) 171
N2—H2N2O1
i
0.90 1.97 2.853 (2) 168
Symmetry code: (i) x;yþ1
2;z1
2.
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).
This research was supported by Universiti Sains Malaysia
(USM) under the University Research grant (No. 1001/
PFARMASI/815004) and the Ministry of Science, Technology
and Innovation through an R&D Initiative Grant (09-05-IFN-
MEB 004). HKF and MMR also thank USM for the Research
University Grant (No. 1001/PFIZIK/811160). MRA gratefully
acknowledges a PhD scholarship from Universiti Malaysia
Sarawak.
Supplementary data and figures for this paper are available from the
IUCr electronic archives (Reference: FJ2327).
References
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem.
Int. Ed. Engl. 34, 1555–1573.
Bruker (2009). APEX2,SAINT and SADABS. Bruker AXS Inc., Madison,
Wisconsin, USA.
Dhar, D. N. & Taploo, C. L. (1982). J. Sci. Ind. Res.41, 501–506.
Jeffrey, G. A. (1997). An Introduction to Hydrogen Bonding. Oxford
University Press.
Jeffrey, G. A. & Saenger, W. (1991). Hydrogen Bonding in Biological
Structures. Berlin: Springer.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Spek, A. L. (2009). Acta Cryst. D65, 148–155.
organic compounds
o2496 Asaruddin et al. doi:10.1107/S1600536810034811 Acta Cryst. (2010). E66, o2496
Acta Crystallographica Section E
Structure Reports
Online
ISSN 1600-5368
‡ Additional correspondence author, e-mail: habibah@ipharm.gov.my or
habibahw@usm.my. Institute of Pharmaceutical and Neutraceuticals, Malaysia
Ministry of Science and Technology and Innovation Science Complex, 11900,
Penang, Malaysia.
§ Thomson Reuters ResearcherID: A-3561-2009.

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Acta Cryst. (2010). E66, o2496
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Acta Cryst. (2010). E66, o2496 [doi:10.1107/S1600536810034811]
2-Amino-4,6-dimethylpyridinium benzoate
Mohd Razip Asaruddin, Habibah A Wahab, Nornisah Mohamed, Mohd Mustaqim Rosli and
Hoong-Kun Fun
S1. Comment
This compound is derived from 2-amino-4,6-dimethylpyridine and benzaldehyde. Schiff bases provide more potential
sites for both chemical and biological activities of compounds. Schiff bases with azomethine linkage were used as anti-
infectious agents (Dhar et al., 1982). Pyridine and its derivatives play an important role in heterocyclic chemistry (Jeffrey,
1997). They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991).
The title 1:1 adduct compound contains an 2-amino-4,6-dimethylpyridinium cation and benzoate anion in the
asymmetric unit. The parameters in (I), (Fig. 1), are within normal ranges. The 2-amino-4,6-dimethylpyridinium cation is
planar with the maximum deviation of 0.005 (2)Å for atom C9. The H atoms of the methyl groups are disordered over
two positions and with fixed site-occupancy factors of 0.50:0.50 for both of the methyl groups. The carboxylate group in
benzoate anion is slightly twisted and make a dihedral angle of 7.2 (1)° with the attached benzene ring.
The 2-amino-4,6-dimethylpyridinium cation and benzoate anion groups are linked together by intermolecular N1—
H1N1···O2 and N2—H1N2···O1 interactions (Table 1) forming an R22(8) ring motif. In the crystal structure, the
molecules stabilized by intermolecular N—H···O hydrogen bonds (Table 1) and π-π interactions with Cg1—Cg2 =
3.661 (2)Å (Cg1 = N1/C8-C12, Cg2 = C1-C6).
S2. Experimental
An ethanol solution (20 ml) of 2-amino-4,6-dimethylpyridine (1.22 g, Aldrich) and benzaldehyde (1.06 g, Merck) were
mixed, heated on a hot plate and stirred with a magnetic stirrer. The reaction mixture was refluxed for 4h. The resulting
condensation solution was allowed to cool slowly at room temperature to form brownish materials. Purification was done
using thin layer chromatography (TLC) and silica gel column chromatography (CC) eluted by chloroform:methanol and
n-hexane:ethyl acetate solvent system. Finally the pure compound was recrystallized in ethanol which afforded the
C7H11N2+.C7H5O2- salt.
S3. Refinement
N bound H atoms was located from a difference Fourier map and were refined using a riding model, with Uiso(H) =
1.2Ueq(N). The methyl hydrogen atoms were located from the difference Fourier map and refined freely with the parent
atom [Uiso(H) = 1.5Ueq(C)]. The rest of the hydrogen atoms were positioned geometrically and refined as riding model
[Uiso(H) = 1.2Ueq(C)].

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Acta Cryst. (2010). E66, o2496
Figure 1
The molecular structure, showing 30% probability displacement ellipsoids and the atom-numbering scheme. Hydrogen
atoms are shown as spheres of arbitrary radius. Dashed lines indicate hydrogen bonds.
Figure 2
The crystal packing of (I) viewed along the c axis. Dashed lines indicate hydrogen bonds. H atoms not involved in the
hydrogen bond interactions have been omitted for clarity.
2-Amino-4,6-dimethylpyridinium benzoate
Crystal data
C7H11N2+·C7H5O2−
Mr = 244.29
Monoclinic, P21/c
Hall symbol: -P 2ybc
a = 7.5362 (16) Å
b = 22.937 (4) Å
c = 8.2124 (14) Å
β = 109.820 (2)°
V = 1335.5 (4) Å3
Z = 4
F(000) = 520
Dx = 1.215 Mg m−3
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 1881 reflections
θ = 2.8–30.1°
µ = 0.08 mm−1
T = 296 K
Plate, colourless
0.57 × 0.23 × 0.05 mm
Data collection
Bruker SMART APEXII CCD area-detector
diffractometer
Radiation source: fine-focus sealed tube
Graphite monochromator
φ and ω scans
Absorption correction: multi-scan
(SADABS;p Bruker, 2009)
Tmin = 0.954, Tmax = 0.996
7639 measured reflections
2336 independent reflections
1527 reflections with I > 2σ(I)

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Acta Cryst. (2010). E66, o2496
Rint = 0.029
θmax = 25.0°, θmin = 2.8°
h = −8→8
k = −27→26
l = −9→9
Refinement
Refinement on F2
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.044
wR(F2) = 0.127
S = 1.02
2336 reflections
199 parameters
0 restraints
Primary atom site location: structure-invariant
direct methods
Secondary atom site location: difference Fourier
map
Hydrogen site location: inferred from
neighbouring sites
H atoms treated by a mixture of independent
and constrained refinement
w = 1/[σ2(Fo2) + (0.0636P)2 + 0.0715P]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max < 0.001
Δρmax = 0.10 e Å−3
Δρmin = −0.14 e Å−3
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance
matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles;
correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate
(isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2,
conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is
used only for calculating R-factors(gt) 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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
xyz U
iso*/Ueq Occ. (<1)
O1 0.5868 (2) 0.30973 (6) 0.23891 (18) 0.0874 (5)
O2 0.5079 (2) 0.40213 (6) 0.18422 (17) 0.0833 (5)
C1 0.6431 (3) 0.42956 (9) 0.5357 (3) 0.0703 (5)
H1A 0.5807 0.4584 0.4578 0.084*
C2 0.7115 (3) 0.44196 (11) 0.7090 (3) 0.0868 (6)
H2A 0.6943 0.4789 0.7480 0.104*
C3 0.8046 (3) 0.40029 (12) 0.8240 (3) 0.0924 (7)
H3A 0.8500 0.4087 0.9418 0.111*
C4 0.8316 (3) 0.34597 (11) 0.7670 (3) 0.0872 (7)
H4A 0.8968 0.3177 0.8460 0.105*
C5 0.7621 (3) 0.33309 (9) 0.5921 (3) 0.0722 (5)
H5A 0.7807 0.2962 0.5535 0.087*
C6 0.6651 (2) 0.37496 (8) 0.4747 (2) 0.0583 (5)
C7 0.5808 (3) 0.36135 (8) 0.2857 (2) 0.0635 (5)
N1 0.33910 (19) 0.38091 (6) −0.15464 (18) 0.0574 (4)
H1N1 0.3994 0.3858 −0.0211 0.069*
N2 0.4633 (2) 0.28852 (6) −0.1151 (2) 0.0734 (5)
H1N2 0.5218 0.2955 0.0136 0.088*
H2N2 0.4965 0.2603 −0.1752 0.088*
C8 0.2395 (2) 0.42572 (7) −0.2537 (2) 0.0616 (5)
C9 0.1624 (3) 0.41807 (9) −0.4262 (3) 0.0703 (5)

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Acta Cryst. (2010). E66, o2496
H9A 0.0956 0.4485 −0.4947 0.084*
C10 0.1811 (3) 0.36533 (9) −0.5041 (2) 0.0692 (5)
C11 0.2816 (3) 0.32162 (8) −0.4016 (2) 0.0660 (5)
H11A 0.2959 0.2863 −0.4511 0.079*
C12 0.3632 (3) 0.32926 (7) −0.2236 (2) 0.0582 (5)
C13 0.2269 (4) 0.47999 (10) −0.1583 (4) 0.0817 (7)
H13A 0.086 (9) 0.490 (3) −0.181 (9) 0.123* 0.50
H13B 0.285 (10) 0.475 (3) −0.023 (9) 0.123* 0.50
H13C 0.298 (10) 0.513 (2) −0.195 (8) 0.123* 0.50
H13D 0.155 (12) 0.506 (3) −0.232 (7) 0.123* 0.50
H13E 0.344 (8) 0.494 (3) −0.087 (10) 0.123* 0.50
H13F 0.184 (10) 0.470 (3) −0.045 (10) 0.123* 0.50
C14 0.0940 (5) 0.3577 (2) −0.6963 (3) 0.0984 (8)
H14A 0.143 (11) 0.323 (5) −0.738 (10) 0.148* 0.50
H14B 0.117 (14) 0.392 (3) −0.758 (11) 0.148* 0.50
H14C −0.041 (12) 0.347 (3) −0.724 (9) 0.148* 0.50
H14D 0.071 (13) 0.319 (5) −0.722 (11) 0.148* 0.50
H14E 0.179 (10) 0.376 (5) −0.759 (10) 0.148* 0.50
H14F −0.037 (11) 0.382 (3) −0.749 (9) 0.148* 0.50
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
O1 0.1331 (13) 0.0527 (8) 0.0720 (9) −0.0037 (8) 0.0288 (8) 0.0009 (7)
O2 0.1135 (12) 0.0558 (8) 0.0663 (9) −0.0009 (7) 0.0119 (8) 0.0059 (7)
C1 0.0710 (12) 0.0710 (13) 0.0675 (13) 0.0012 (10) 0.0216 (10) −0.0006 (10)
C2 0.0918 (16) 0.0927 (16) 0.0724 (15) 0.0031 (12) 0.0231 (12) −0.0119 (13)
C3 0.0939 (16) 0.114 (2) 0.0648 (14) −0.0117 (14) 0.0210 (12) −0.0052 (14)
C4 0.0785 (14) 0.0990 (18) 0.0745 (15) −0.0042 (12) 0.0135 (11) 0.0235 (13)
C5 0.0718 (12) 0.0666 (12) 0.0748 (14) −0.0054 (9) 0.0204 (10) 0.0104 (10)
C6 0.0551 (10) 0.0569 (11) 0.0638 (11) −0.0076 (8) 0.0212 (8) 0.0039 (9)
C7 0.0713 (12) 0.0520 (11) 0.0673 (12) −0.0098 (9) 0.0238 (9) 0.0053 (10)
N1 0.0639 (9) 0.0481 (8) 0.0611 (9) −0.0003 (7) 0.0223 (7) 0.0034 (7)
N2 0.1069 (13) 0.0532 (9) 0.0645 (10) 0.0139 (8) 0.0348 (9) 0.0070 (8)
C8 0.0552 (10) 0.0549 (11) 0.0730 (13) 0.0005 (8) 0.0192 (9) 0.0079 (9)
C9 0.0616 (11) 0.0704 (13) 0.0755 (14) 0.0094 (9) 0.0187 (10) 0.0136 (10)
C10 0.0580 (11) 0.0871 (14) 0.0641 (12) 0.0035 (10) 0.0228 (9) 0.0068 (11)
C11 0.0721 (12) 0.0667 (12) 0.0664 (12) 0.0017 (9) 0.0328 (10) −0.0042 (9)
C12 0.0643 (11) 0.0513 (10) 0.0650 (12) 0.0000 (8) 0.0297 (9) 0.0049 (9)
C13 0.0840 (17) 0.0544 (13) 0.0937 (19) 0.0083 (11) 0.0132 (14) −0.0013 (12)
C14 0.093 (2) 0.130 (3) 0.0671 (15) 0.014 (2) 0.0203 (14) 0.0021 (16)
Geometric parameters (Å, º)
O1—C7 1.250 (2) C8—C9 1.348 (3)
O2—C7 1.249 (2) C8—C13 1.491 (3)
C1—C2 1.369 (3) C9—C10 1.398 (3)
C1—C6 1.380 (3) C9—H9A 0.9300

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Acta Cryst. (2010). E66, o2496
C1—H1A 0.9300 C10—C11 1.362 (3)
C2—C3 1.360 (3) C10—C14 1.500 (3)
C2—H2A 0.9300 C11—C12 1.391 (3)
C3—C4 1.370 (3) C11—H11A 0.9300
C3—H3A 0.9300 C13—H13A 1.04 (6)
C4—C5 1.384 (3) C13—H13B 1.06 (7)
C4—H4A 0.9300 C13—H13C 1.04 (5)
C5—C6 1.381 (3) C13—H13D 0.89 (6)
C5—H5A 0.9300 C13—H13E 0.93 (6)
C6—C7 1.497 (3) C13—H13F 1.11 (7)
N1—C12 1.352 (2) C14—H14A 0.99 (9)
N1—C8 1.367 (2) C14—H14B 0.98 (10)
N1—H1N1 1.0414 C14—H14C 1.00 (8)
N2—C12 1.335 (2) C14—H14D 0.90 (10)
N2—H1N2 1.0101 C14—H14E 1.03 (10)
N2—H2N2 0.9002 C14—H14F 1.09 (7)
C2—C1—C6 121.1 (2) N1—C12—C11 118.47 (16)
C2—C1—H1A 119.4 C8—C13—H13A 109 (3)
C6—C1—H1A 119.4 C8—C13—H13B 112 (3)
C3—C2—C1 120.0 (2) H13A—C13—H13B 104 (4)
C3—C2—H2A 120.0 C8—C13—H13C 109 (3)
C1—C2—H2A 120.0 H13A—C13—H13C 113 (4)
C2—C3—C4 120.2 (2) H13B—C13—H13C 109 (4)
C2—C3—H3A 119.9 C8—C13—H13D 109 (4)
C4—C3—H3A 119.9 H13A—C13—H13D 52 (4)
C3—C4—C5 120.1 (2) H13B—C13—H13D 137 (5)
C3—C4—H4A 120.0 H13C—C13—H13D 65 (4)
C5—C4—H4A 120.0 C8—C13—H13E 113 (4)
C6—C5—C4 120.0 (2) H13A—C13—H13E 137 (4)
C6—C5—H5A 120.0 H13B—C13—H13E 54 (4)
C4—C5—H5A 120.0 H13C—C13—H13E 57 (4)
C1—C6—C5 118.58 (18) H13D—C13—H13E 116 (5)
C1—C6—C7 120.30 (16) C8—C13—H13F 111 (3)
C5—C6—C7 121.10 (17) H13A—C13—H13F 68 (4)
O2—C7—O1 123.88 (17) H13C—C13—H13F 136 (4)
O2—C7—C6 118.14 (16) H13D—C13—H13F 115 (5)
O1—C7—C6 117.98 (16) H13E—C13—H13F 92 (5)
C12—N1—C8 122.30 (16) C10—C14—H14A 112 (5)
C12—N1—H1N1 117.7 C10—C14—H14B 111 (5)
C8—N1—H1N1 120.0 H14A—C14—H14B 108 (6)
C12—N2—H1N2 122.4 C10—C14—H14C 108 (4)
C12—N2—H2N2 109.7 H14A—C14—H14C 102 (7)
H1N2—N2—H2N2 125.7 H14B—C14—H14C 115 (6)
C9—C8—N1 118.79 (17) C10—C14—H14D 110 (6)
C9—C8—C13 125.41 (18) H14B—C14—H14D 135 (7)
N1—C8—C13 115.79 (18) H14C—C14—H14D 67 (5)
C8—C9—C10 121.30 (17) C10—C14—H14E 111 (4)

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Acta Cryst. (2010). E66, o2496
C8—C9—H9A 119.4 H14A—C14—H14E 77 (5)
C10—C9—H9A 119.4 H14C—C14—H14E 138 (5)
C11—C10—C9 118.37 (18) H14D—C14—H14E 112 (7)
C11—C10—C14 121.2 (2) C10—C14—H14F 112 (3)
C9—C10—C14 120.5 (2) H14A—C14—H14F 132 (6)
C10—C11—C12 120.77 (18) H14B—C14—H14F 72 (5)
C10—C11—H11A 119.6 H14C—C14—H14F 46 (4)
C12—C11—H11A 119.6 H14D—C14—H14F 109 (7)
N2—C12—N1 117.34 (16) H14E—C14—H14F 104 (6)
N2—C12—C11 124.19 (17)
C6—C1—C2—C3 0.7 (3) C12—N1—C8—C9 0.1 (2)
C1—C2—C3—C4 0.5 (4) C12—N1—C8—C13 −179.6 (2)
C2—C3—C4—C5 −0.8 (4) N1—C8—C9—C10 0.7 (3)
C3—C4—C5—C6 −0.1 (3) C13—C8—C9—C10 −179.7 (2)
C2—C1—C6—C5 −1.6 (3) C8—C9—C10—C11 −0.8 (3)
C2—C1—C6—C7 176.91 (18) C8—C9—C10—C14 179.9 (2)
C4—C5—C6—C1 1.3 (3) C9—C10—C11—C12 0.2 (3)
C4—C5—C6—C7 −177.18 (18) C14—C10—C11—C12 179.5 (2)
C1—C6—C7—O2 7.2 (3) C8—N1—C12—N2 179.88 (16)
C5—C6—C7—O2 −174.36 (18) C8—N1—C12—C11 −0.6 (2)
C1—C6—C7—O1 −172.47 (18) C10—C11—C12—N2 179.94 (18)
C5—C6—C7—O1 6.0 (3) C10—C11—C12—N1 0.5 (3)
Hydrogen-bond geometry (Å, º)
D—H···AD—H H···AD···AD—H···A
N1—H1N1···O2 1.04 1.65 2.683 (2) 172
N2—H1N2···O1 1.01 1.78 2.779 (2) 171
N2—H2N2···O1i0.90 1.97 2.853 (2) 168
Symmetry code: (i) x, −y+1/2, z−1/2.