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The title compound, C6H9N2+·C2H3O2, contains eight- and sixteen-membered hydrogen-bonded rings involving 2-amino-3-methyl­pyridinium and acetate ions. The 2-amino-3-methyl­pyridinium and acetate ions are linked into zigzag chains by C—H...O and N—H...O hydrogen bonds. The dihedral angle between the 2-amino-3-methyl­pyridinium ring and the hydrogen-bonded acetate ion is 6.63 (6)°. The heterocycle is fully protonated, enabling amine–imine tautomerization.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805041255/jh6030sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536805041255/jh6030Isup2.hkl
Contains datablock I

CCDC reference: 296595

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.043
  • wR factor = 0.120
  • Data-to-parameter ratio = 14.2

checkCIF/PLATON results

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Alert level C PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size ....... 0.64 mm PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C7 PLAT353_ALERT_3_C Long N-H Bond (0.87A) N1 - H1 ... 1.01 Ang.
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

Hydrogen bonding plays a key role in molecular recognition (Goswami & Ghosh, 1997) and crystal engineering research (Goswami et al., 1998). The design of highly specific solid-state compounds is of considerable significance in organic chemistry due to the important applications of these compounds in the development of new optical, magnetic and electronic systems (Lehn, 1992). 2-Aminopyridine and its derivatives are used in the manufacture of pharmaceuticals, hair dyes and other dyes. The present work is part of a structural study of compound of 2-amino-3-methylpyridinium systems with hydrogen-bond donors and we report here the structure of 2-amino-3-methylpyridinium acetate, (I) (Fig. 1).

In (I), the 2-amino-3-methylpyridinium ions are linked to the acetate ions through N1—H1···O1 and N2—H2A···O2 hydrogen bonds, resulting in the formation of cyclic eight-membered hydrogen-bonded rings (Fig. 1 and Table 2). The eight-membered hydrogen-bonded rings are linked by N2—H2B···O2 and C5—H5···O1 hydrogen bonds forming two-dimensional network. The hydrogen-bonded planes (two-dimensional network) are arranged so that C6—H6···O1 hydrogen bonds form R344[16] rings, resulting in a three-dimensional network (Fig. 2).

The 2-aminopyridine–carboxylic acid system has been the subject of theoretical (Inuzuka & Fujimoto, 1990) and spectroscopic (Inuzuka & Fujimoto, 1986) amine–imine tautomerization studies. 2-Aminopyridine and derivatives, like other organic bases, are protonated in acidic solution. The bonding of the H atom to the ring N atom of 2-aminopyridine rather than the amine N atom gives an ion for which an additional resonance structure can be written. As this monocation has more resonance energy (additional ionic resonance) than 2-aminopyridine itself, 2-aminopyridine is a strong base, like amidines (Acheson, 1967).

The present investigation, like our previous work (Büyükgüngör & Odabaşoğlu, 2002, 2003; Odabaşoğlu, Büyükgüngör & Lönnecke, 2003; Odabaşoğlu, Büyükgüngör, Turgut et al., 2003; Büyükgüngör et al., 2004), clearly shows that the positive charge in the 2-aminopyridinium ion is on the amine group. Our investigations also show that the 2-amino-3-methylpyridinium cation is present in the crystal structure in a similar form and the methyl H atoms in the acetate show rotational disorder.

The C1—N2 bond is length approximately equal to that of a CN double bond (Shanmuga Sundara Raj, Fun, Lu et al., 2000), indicating that atom N2 of the amine group must also be sp2 hybridized. This is also supported by the C1—N2—H2A angle of 117.2 (11)° (Table 1). Similar bond distances and angles have been observed in 2-aminopyridinium succinate succinic acid (Büyükgüngör & Odabaşoğlu, 2002), 2-aminopyridinium adipate monoadipic acid dihydrate (Odabaşoğlu, Büyükgüngör, Turgut et al., 2003), bis(2-aminopyridinium) maleate (Büyükgüngör & Odabaşoğlu, 2003), 2-aminopyridinium fumarate fumaric acid (Büyükgüngör et al., 2004) and in some 2-aminopyridine containing molecules (Yang et al., 1995; Grobelny et al., 1995; Shanmuga Sundara Raj, Fun, Zhao et al., 2000).

Experimental top

The title compound was prepared by mixing 3-methyl-2-aminopyridine and acetic acid in a 1:1 molar ratio in water at 353 K. Crystals of (I) were obtained by slow evaporation of the solvent (m.p. 370–372 K).

Refinement top

Refined C—H distances are in the range 0.94 (2)–0.98 (2) Å and Uiso values for H atoms are in the range 0.056 (4)–0.097 (7) Å2. The H atoms bounded to C8 were refined as an idealized disordered methyl group (two positions) in their calculated positions, with Uiso(H) = 1.5Ueq of the parent atom.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. A view of the molecule of (I) with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probalitity level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. A packing diagram of the title compound, showing the hydrogen-bonding scheme (dashed lines).
2-amino-3-methylprydinium acetate top
Crystal data top
C6H9N2+·C2H3O2Z = 2
Mr = 168.20F(000) = 180
Triclinic, P1Dx = 1.275 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.0451 (8) ÅCell parameters from 7421 reflections
b = 8.0502 (10) Åθ = 2.6–28.0°
c = 8.5061 (10) ŵ = 0.09 mm1
α = 65.756 (9)°T = 296 K
β = 86.505 (9)°Plate, colorless
γ = 85.326 (9)°0.64 × 0.49 × 0.24 mm
V = 438.21 (10) Å3
Data collection top
Stoe IPDS-II
diffractometer
1646 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.073
Plane graphite monochromatorθmax = 27.7°, θmin = 2.8°
Detector resolution: 6.67 pixels mm-1h = 98
rotation method scansk = 1010
7421 measured reflectionsl = 1111
2054 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.121H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.054P)2 + 0.0553P]
where P = (Fo2 + 2Fc2)/3
2054 reflections(Δ/σ)max < 0.001
145 parametersΔρmax = 0.19 e Å3
0 restraintsΔρmin = 0.17 e Å3
Crystal data top
C6H9N2+·C2H3O2γ = 85.326 (9)°
Mr = 168.20V = 438.21 (10) Å3
Triclinic, P1Z = 2
a = 7.0451 (8) ÅMo Kα radiation
b = 8.0502 (10) ŵ = 0.09 mm1
c = 8.5061 (10) ÅT = 296 K
α = 65.756 (9)°0.64 × 0.49 × 0.24 mm
β = 86.505 (9)°
Data collection top
Stoe IPDS-II
diffractometer
1646 reflections with I > 2σ(I)
7421 measured reflectionsRint = 0.073
2054 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0430 restraints
wR(F2) = 0.121H atoms treated by a mixture of independent and constrained refinement
S = 1.04Δρmax = 0.19 e Å3
2054 reflectionsΔρmin = 0.17 e Å3
145 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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) top
xyzUiso*/UeqOcc. (<1)
C10.48331 (16)0.78843 (16)0.39524 (15)0.0413 (3)
C20.60971 (17)0.78674 (17)0.52011 (16)0.0451 (3)
C30.5650 (2)0.6853 (2)0.68885 (18)0.0561 (3)
C40.4028 (2)0.5851 (2)0.74037 (18)0.0591 (4)
C50.28844 (19)0.58748 (18)0.61765 (17)0.0513 (3)
C60.7862 (2)0.8901 (2)0.4611 (2)0.0581 (4)
C70.11314 (18)0.75965 (17)0.07288 (16)0.0472 (3)
C80.0405 (2)0.7631 (2)0.04431 (19)0.0624 (4)
H8A0.14420.69510.02370.094*0.50
H8B0.01030.70940.12120.094*0.50
H8C0.08560.88710.11010.094*0.50
H8D0.00210.83260.16210.094*0.50
H8E0.15660.81830.01720.094*0.50
H8F0.06070.64060.02830.094*0.50
N10.32929 (14)0.68791 (14)0.44885 (13)0.0453 (3)
N20.50971 (18)0.88402 (17)0.22719 (14)0.0557 (3)
O10.08560 (14)0.67309 (15)0.23200 (12)0.0630 (3)
O20.25814 (16)0.84162 (18)0.00586 (13)0.0722 (4)
H10.243 (3)0.685 (2)0.360 (2)0.075 (5)*
H2A0.427 (3)0.870 (2)0.156 (2)0.070 (5)*
H2B0.608 (3)0.958 (2)0.189 (2)0.068 (5)*
H30.651 (3)0.687 (3)0.777 (3)0.081 (5)*
H40.373 (3)0.516 (3)0.859 (3)0.074 (5)*
H50.177 (2)0.521 (2)0.639 (2)0.056 (4)*
H6A0.866 (3)0.839 (3)0.386 (3)0.090 (6)*
H6B0.754 (3)1.019 (3)0.385 (3)0.097 (7)*
H6C0.853 (3)0.883 (3)0.561 (3)0.086 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0394 (6)0.0444 (6)0.0391 (6)0.0094 (4)0.0011 (4)0.0147 (5)
C20.0413 (6)0.0504 (6)0.0446 (6)0.0094 (5)0.0037 (5)0.0188 (5)
C30.0567 (8)0.0675 (8)0.0424 (7)0.0149 (6)0.0073 (5)0.0180 (6)
C40.0667 (8)0.0662 (8)0.0372 (6)0.0212 (7)0.0028 (6)0.0112 (6)
C50.0503 (7)0.0541 (7)0.0461 (7)0.0192 (6)0.0055 (5)0.0149 (5)
C60.0457 (7)0.0741 (10)0.0558 (8)0.0205 (6)0.0024 (6)0.0246 (7)
C70.0470 (6)0.0517 (7)0.0429 (6)0.0146 (5)0.0015 (5)0.0171 (5)
C80.0567 (8)0.0774 (9)0.0524 (8)0.0207 (7)0.0098 (6)0.0215 (7)
N10.0427 (5)0.0500 (5)0.0412 (6)0.0141 (4)0.0014 (4)0.0148 (4)
N20.0543 (6)0.0680 (7)0.0388 (6)0.0277 (5)0.0022 (5)0.0111 (5)
O10.0552 (6)0.0829 (7)0.0426 (5)0.0308 (5)0.0033 (4)0.0121 (5)
O20.0661 (6)0.1001 (8)0.0442 (5)0.0458 (6)0.0000 (4)0.0159 (5)
Geometric parameters (Å, º) top
C1—N21.3258 (16)C6—H6C0.97 (2)
C1—N11.3491 (15)C7—O21.2385 (15)
C1—C21.4222 (16)C7—O11.2532 (15)
C2—C31.3603 (19)C7—C81.5066 (18)
C2—C61.4964 (18)C8—H8A0.9600
C3—C41.396 (2)C8—H8B0.9600
C3—H31.00 (2)C8—H8C0.9600
C4—C51.350 (2)C8—H8D0.9600
C4—H40.95 (2)C8—H8E0.9600
C5—N11.3536 (16)C8—H8F0.9600
C5—H50.954 (17)N1—H11.01 (2)
C6—H6A1.01 (2)N2—H2A0.910 (19)
C6—H6B0.99 (2)N2—H2B0.903 (19)
N2—C1—N1117.94 (10)H8A—C8—H8B109.5
N2—C1—C2123.09 (11)C7—C8—H8C109.5
N1—C1—C2118.97 (10)H8A—C8—H8C109.5
C3—C2—C1117.38 (11)H8B—C8—H8C109.5
C3—C2—C6123.32 (12)C7—C8—H8D109.5
C1—C2—C6119.28 (11)H8A—C8—H8D141.1
C2—C3—C4122.27 (12)H8B—C8—H8D56.3
C2—C3—H3117.7 (12)H8C—C8—H8D56.3
C4—C3—H3120.0 (12)C7—C8—H8E109.5
C5—C4—C3118.51 (12)H8A—C8—H8E56.3
C5—C4—H4120.2 (12)H8B—C8—H8E141.1
C3—C4—H4121.2 (11)H8C—C8—H8E56.3
C4—C5—N1120.39 (12)H8D—C8—H8E109.5
C4—C5—H5125.0 (10)C7—C8—H8F109.5
N1—C5—H5114.6 (10)H8A—C8—H8F56.3
C2—C6—H6A108.2 (12)H8B—C8—H8F56.3
C2—C6—H6B110.8 (13)H8C—C8—H8F141.1
H6A—C6—H6B105.1 (17)H8D—C8—H8F109.5
C2—C6—H6C109.5 (12)H8E—C8—H8F109.5
H6A—C6—H6C113.2 (16)C1—N1—C5122.47 (10)
H6B—C6—H6C109.9 (18)C1—N1—H1118.9 (11)
O2—C7—O1124.41 (12)C5—N1—H1118.7 (11)
O2—C7—C8118.00 (12)C1—N2—H2A117.1 (12)
O1—C7—C8117.58 (12)C1—N2—H2B119.5 (11)
C7—C8—H8A109.5H2A—N2—H2B123.4 (16)
C7—C8—H8B109.5
N2—C1—C2—C3178.99 (13)C2—C3—C4—C51.0 (3)
N1—C1—C2—C31.30 (19)C3—C4—C5—N11.2 (2)
N2—C1—C2—C62.9 (2)N2—C1—N1—C5179.15 (12)
N1—C1—C2—C6176.84 (13)C2—C1—N1—C51.12 (19)
C1—C2—C3—C40.3 (2)C4—C5—N1—C10.2 (2)
C6—C2—C3—C4177.79 (15)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···O20.910 (19)1.890 (19)2.7992 (15)179.2 (18)
N2—H2B···O2i0.903 (19)2.026 (18)2.8426 (16)149.7 (16)
N1—H1···O11.01 (2)1.64 (2)2.6390 (14)173.9 (17)
C5—H5···O1ii0.954 (17)2.424 (17)3.3566 (16)165.7 (14)
C6—H6A···O1iii1.01 (2)2.60 (2)3.605 (2)172.2 (16)
Symmetry codes: (i) x+1, y+2, z; (ii) x, y+1, z+1; (iii) x+1, y, z.

Experimental details

Crystal data
Chemical formulaC6H9N2+·C2H3O2
Mr168.20
Crystal system, space groupTriclinic, P1
Temperature (K)296
a, b, c (Å)7.0451 (8), 8.0502 (10), 8.5061 (10)
α, β, γ (°)65.756 (9), 86.505 (9), 85.326 (9)
V3)438.21 (10)
Z2
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.64 × 0.49 × 0.24
Data collection
DiffractometerStoe IPDS-II
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
7421, 2054, 1646
Rint0.073
(sin θ/λ)max1)0.655
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.043, 0.121, 1.04
No. of reflections2054
No. of parameters145
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.19, 0.17

Computer programs: X-AREA (Stoe & Cie, 2002), X-AREA, X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
C1—N21.3258 (16)C7—O21.2385 (15)
C1—N11.3491 (15)C7—O11.2532 (15)
C5—N11.3536 (16)
N2—C1—N1117.94 (10)O2—C7—O1124.41 (12)
N2—C1—C2123.09 (11)
N2—C1—C2—C3178.99 (13)N2—C1—N1—C5179.15 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···O20.910 (19)1.890 (19)2.7992 (15)179.2 (18)
N2—H2B···O2i0.903 (19)2.026 (18)2.8426 (16)149.7 (16)
N1—H1···O11.01 (2)1.64 (2)2.6390 (14)173.9 (17)
C5—H5···O1ii0.954 (17)2.424 (17)3.3566 (16)165.7 (14)
C6—H6A···O1iii1.01 (2)2.60 (2)3.605 (2)172.2 (16)
Symmetry codes: (i) x+1, y+2, z; (ii) x, y+1, z+1; (iii) x+1, y, z.
 

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