The title compound, C
6H
9N
2+·C
2H
3O
2−, 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
CCDC reference: 296595
Key indicators
- Single-crystal X-ray study
- T = 296 K
- Mean (C-C) = 0.002 Å
- R factor = 0.043
- wR factor = 0.120
- Data-to-parameter ratio = 14.2
checkCIF/PLATON results
No syntax errors found
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
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).
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.
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).
2-amino-3-methylprydinium acetate
top
Crystal data top
C6H9N2+·C2H3O2− | Z = 2 |
Mr = 168.20 | F(000) = 180 |
Triclinic, P1 | Dx = 1.275 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.0451 (8) Å | Cell parameters from 7421 reflections |
b = 8.0502 (10) Å | θ = 2.6–28.0° |
c = 8.5061 (10) Å | µ = 0.09 mm−1 |
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 tube | Rint = 0.073 |
Plane graphite monochromator | θmax = 27.7°, θmin = 2.8° |
Detector resolution: 6.67 pixels mm-1 | h = −9→8 |
rotation method scans | k = −10→10 |
7421 measured reflections | l = −11→11 |
2054 independent reflections | |
Refinement top
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)] = 0.043 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.121 | H 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 parameters | Δρmax = 0.19 e Å−3 |
0 restraints | Δρmin = −0.17 e Å−3 |
Crystal data top
C6H9N2+·C2H3O2− | γ = 85.326 (9)° |
Mr = 168.20 | V = 438.21 (10) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.0451 (8) Å | Mo Kα radiation |
b = 8.0502 (10) Å | µ = 0.09 mm−1 |
c = 8.5061 (10) Å | T = 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 reflections | Rint = 0.073 |
2054 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.121 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.19 e Å−3 |
2054 reflections | Δρmin = −0.17 e Å−3 |
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 | x | y | z | Uiso*/Ueq | Occ. (<1) |
C1 | 0.48331 (16) | 0.78843 (16) | 0.39524 (15) | 0.0413 (3) | |
C2 | 0.60971 (17) | 0.78674 (17) | 0.52011 (16) | 0.0451 (3) | |
C3 | 0.5650 (2) | 0.6853 (2) | 0.68885 (18) | 0.0561 (3) | |
C4 | 0.4028 (2) | 0.5851 (2) | 0.74037 (18) | 0.0591 (4) | |
C5 | 0.28844 (19) | 0.58748 (18) | 0.61765 (17) | 0.0513 (3) | |
C6 | 0.7862 (2) | 0.8901 (2) | 0.4611 (2) | 0.0581 (4) | |
C7 | 0.11314 (18) | 0.75965 (17) | 0.07288 (16) | 0.0472 (3) | |
C8 | −0.0405 (2) | 0.7631 (2) | −0.04431 (19) | 0.0624 (4) | |
H8A | −0.1442 | 0.6951 | 0.0237 | 0.094* | 0.50 |
H8B | 0.0103 | 0.7094 | −0.1212 | 0.094* | 0.50 |
H8C | −0.0856 | 0.8871 | −0.1101 | 0.094* | 0.50 |
H8D | −0.0021 | 0.8326 | −0.1621 | 0.094* | 0.50 |
H8E | −0.1566 | 0.8183 | −0.0172 | 0.094* | 0.50 |
H8F | −0.0607 | 0.6406 | −0.0283 | 0.094* | 0.50 |
N1 | 0.32929 (14) | 0.68791 (14) | 0.44885 (13) | 0.0453 (3) | |
N2 | 0.50971 (18) | 0.88402 (17) | 0.22719 (14) | 0.0557 (3) | |
O1 | 0.08560 (14) | 0.67309 (15) | 0.23200 (12) | 0.0630 (3) | |
O2 | 0.25814 (16) | 0.84162 (18) | 0.00586 (13) | 0.0722 (4) | |
H1 | 0.243 (3) | 0.685 (2) | 0.360 (2) | 0.075 (5)* | |
H2A | 0.427 (3) | 0.870 (2) | 0.156 (2) | 0.070 (5)* | |
H2B | 0.608 (3) | 0.958 (2) | 0.189 (2) | 0.068 (5)* | |
H3 | 0.651 (3) | 0.687 (3) | 0.777 (3) | 0.081 (5)* | |
H4 | 0.373 (3) | 0.516 (3) | 0.859 (3) | 0.074 (5)* | |
H5 | 0.177 (2) | 0.521 (2) | 0.639 (2) | 0.056 (4)* | |
H6A | 0.866 (3) | 0.839 (3) | 0.386 (3) | 0.090 (6)* | |
H6B | 0.754 (3) | 1.019 (3) | 0.385 (3) | 0.097 (7)* | |
H6C | 0.853 (3) | 0.883 (3) | 0.561 (3) | 0.086 (6)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0394 (6) | 0.0444 (6) | 0.0391 (6) | −0.0094 (4) | −0.0011 (4) | −0.0147 (5) |
C2 | 0.0413 (6) | 0.0504 (6) | 0.0446 (6) | −0.0094 (5) | −0.0037 (5) | −0.0188 (5) |
C3 | 0.0567 (8) | 0.0675 (8) | 0.0424 (7) | −0.0149 (6) | −0.0073 (5) | −0.0180 (6) |
C4 | 0.0667 (8) | 0.0662 (8) | 0.0372 (6) | −0.0212 (7) | 0.0028 (6) | −0.0112 (6) |
C5 | 0.0503 (7) | 0.0541 (7) | 0.0461 (7) | −0.0192 (6) | 0.0055 (5) | −0.0149 (5) |
C6 | 0.0457 (7) | 0.0741 (10) | 0.0558 (8) | −0.0205 (6) | −0.0024 (6) | −0.0246 (7) |
C7 | 0.0470 (6) | 0.0517 (7) | 0.0429 (6) | −0.0146 (5) | −0.0015 (5) | −0.0171 (5) |
C8 | 0.0567 (8) | 0.0774 (9) | 0.0524 (8) | −0.0207 (7) | −0.0098 (6) | −0.0215 (7) |
N1 | 0.0427 (5) | 0.0500 (5) | 0.0412 (6) | −0.0141 (4) | −0.0014 (4) | −0.0148 (4) |
N2 | 0.0543 (6) | 0.0680 (7) | 0.0388 (6) | −0.0277 (5) | −0.0022 (5) | −0.0111 (5) |
O1 | 0.0552 (6) | 0.0829 (7) | 0.0426 (5) | −0.0308 (5) | −0.0033 (4) | −0.0121 (5) |
O2 | 0.0661 (6) | 0.1001 (8) | 0.0442 (5) | −0.0458 (6) | 0.0000 (4) | −0.0159 (5) |
Geometric parameters (Å, º) top
C1—N2 | 1.3258 (16) | C6—H6C | 0.97 (2) |
C1—N1 | 1.3491 (15) | C7—O2 | 1.2385 (15) |
C1—C2 | 1.4222 (16) | C7—O1 | 1.2532 (15) |
C2—C3 | 1.3603 (19) | C7—C8 | 1.5066 (18) |
C2—C6 | 1.4964 (18) | C8—H8A | 0.9600 |
C3—C4 | 1.396 (2) | C8—H8B | 0.9600 |
C3—H3 | 1.00 (2) | C8—H8C | 0.9600 |
C4—C5 | 1.350 (2) | C8—H8D | 0.9600 |
C4—H4 | 0.95 (2) | C8—H8E | 0.9600 |
C5—N1 | 1.3536 (16) | C8—H8F | 0.9600 |
C5—H5 | 0.954 (17) | N1—H1 | 1.01 (2) |
C6—H6A | 1.01 (2) | N2—H2A | 0.910 (19) |
C6—H6B | 0.99 (2) | N2—H2B | 0.903 (19) |
| | | |
N2—C1—N1 | 117.94 (10) | H8A—C8—H8B | 109.5 |
N2—C1—C2 | 123.09 (11) | C7—C8—H8C | 109.5 |
N1—C1—C2 | 118.97 (10) | H8A—C8—H8C | 109.5 |
C3—C2—C1 | 117.38 (11) | H8B—C8—H8C | 109.5 |
C3—C2—C6 | 123.32 (12) | C7—C8—H8D | 109.5 |
C1—C2—C6 | 119.28 (11) | H8A—C8—H8D | 141.1 |
C2—C3—C4 | 122.27 (12) | H8B—C8—H8D | 56.3 |
C2—C3—H3 | 117.7 (12) | H8C—C8—H8D | 56.3 |
C4—C3—H3 | 120.0 (12) | C7—C8—H8E | 109.5 |
C5—C4—C3 | 118.51 (12) | H8A—C8—H8E | 56.3 |
C5—C4—H4 | 120.2 (12) | H8B—C8—H8E | 141.1 |
C3—C4—H4 | 121.2 (11) | H8C—C8—H8E | 56.3 |
C4—C5—N1 | 120.39 (12) | H8D—C8—H8E | 109.5 |
C4—C5—H5 | 125.0 (10) | C7—C8—H8F | 109.5 |
N1—C5—H5 | 114.6 (10) | H8A—C8—H8F | 56.3 |
C2—C6—H6A | 108.2 (12) | H8B—C8—H8F | 56.3 |
C2—C6—H6B | 110.8 (13) | H8C—C8—H8F | 141.1 |
H6A—C6—H6B | 105.1 (17) | H8D—C8—H8F | 109.5 |
C2—C6—H6C | 109.5 (12) | H8E—C8—H8F | 109.5 |
H6A—C6—H6C | 113.2 (16) | C1—N1—C5 | 122.47 (10) |
H6B—C6—H6C | 109.9 (18) | C1—N1—H1 | 118.9 (11) |
O2—C7—O1 | 124.41 (12) | C5—N1—H1 | 118.7 (11) |
O2—C7—C8 | 118.00 (12) | C1—N2—H2A | 117.1 (12) |
O1—C7—C8 | 117.58 (12) | C1—N2—H2B | 119.5 (11) |
C7—C8—H8A | 109.5 | H2A—N2—H2B | 123.4 (16) |
C7—C8—H8B | 109.5 | | |
| | | |
N2—C1—C2—C3 | 178.99 (13) | C2—C3—C4—C5 | 1.0 (3) |
N1—C1—C2—C3 | −1.30 (19) | C3—C4—C5—N1 | −1.2 (2) |
N2—C1—C2—C6 | −2.9 (2) | N2—C1—N1—C5 | −179.15 (12) |
N1—C1—C2—C6 | 176.84 (13) | C2—C1—N1—C5 | 1.12 (19) |
C1—C2—C3—C4 | 0.3 (2) | C4—C5—N1—C1 | 0.2 (2) |
C6—C2—C3—C4 | −177.79 (15) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O2 | 0.910 (19) | 1.890 (19) | 2.7992 (15) | 179.2 (18) |
N2—H2B···O2i | 0.903 (19) | 2.026 (18) | 2.8426 (16) | 149.7 (16) |
N1—H1···O1 | 1.01 (2) | 1.64 (2) | 2.6390 (14) | 173.9 (17) |
C5—H5···O1ii | 0.954 (17) | 2.424 (17) | 3.3566 (16) | 165.7 (14) |
C6—H6A···O1iii | 1.01 (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 formula | C6H9N2+·C2H3O2− |
Mr | 168.20 |
Crystal system, space group | Triclinic, 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) |
V (Å3) | 438.21 (10) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.64 × 0.49 × 0.24 |
|
Data collection |
Diffractometer | Stoe IPDS-II diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7421, 2054, 1646 |
Rint | 0.073 |
(sin θ/λ)max (Å−1) | 0.655 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.121, 1.04 |
No. of reflections | 2054 |
No. of parameters | 145 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.19, −0.17 |
Selected geometric parameters (Å, º) topC1—N2 | 1.3258 (16) | C7—O2 | 1.2385 (15) |
C1—N1 | 1.3491 (15) | C7—O1 | 1.2532 (15) |
C5—N1 | 1.3536 (16) | | |
| | | |
N2—C1—N1 | 117.94 (10) | O2—C7—O1 | 124.41 (12) |
N2—C1—C2 | 123.09 (11) | | |
| | | |
N2—C1—C2—C3 | 178.99 (13) | N2—C1—N1—C5 | −179.15 (12) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O2 | 0.910 (19) | 1.890 (19) | 2.7992 (15) | 179.2 (18) |
N2—H2B···O2i | 0.903 (19) | 2.026 (18) | 2.8426 (16) | 149.7 (16) |
N1—H1···O1 | 1.01 (2) | 1.64 (2) | 2.6390 (14) | 173.9 (17) |
C5—H5···O1ii | 0.954 (17) | 2.424 (17) | 3.3566 (16) | 165.7 (14) |
C6—H6A···O1iii | 1.01 (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. |
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 C═N 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).