organic compounds
2-Amino-4-methylpyridinium trifluoroacetate
aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: hkfun@usm.my
The 6H9N2+·C2F3O2−, contains two independent 2-amino-4-methylpyridinium cations and two independent trifluoroacetate anions. The F atoms of both anions are disordered over two sets of sites, with site occupancies of 0.50 (3) and 0.50 (3) in one of the anions, and 0.756 (9) and 0.244 (9) in the other. In the crystal, the cations and anions are linked into chains along the b axis by N—H⋯O hydrogen bonds and these chains are cross-linked by C—H⋯O hydrogen bonds, forming a two-dimensional network lying parallel to (101). The is further stabilized by π–π interactions between the pyridinium rings [centroid–centroid distances = 3.5842 (13) and 3.5665 (16) Å].
of the title compound, CRelated literature
For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997); Katritzky et al. (1996). For related structures, see: Kvick & Noordik (1977); Shen et al. (2008); Hemamalini & Fun (2010). For trifluoroacetic acid, see: Rodrigues et al. (2001). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2009); cell 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).
Supporting information
10.1107/S1600536810008202/ci5038sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536810008202/ci5038Isup2.hkl
To a hot methanol solution (20 ml) of 2-amino-4-methylpyridine (27 mg, Aldrich) was added a few drops of trifluoroacetic acid. The solution was warmed over a water bath for a few minutes. The resulting solution was allowed to cool slowly to room temperature. Crystals of the title compound appeared after a few days.
Atoms H1NA, H2NA, H3NA, H1NB, H2NB and H3NB were located in a difference Fourier map and refined; the N–H distances of the NH2 groups were restrained to be equal. The remaining H atoms were positioned geometrically [C–H = 0.93 or 0.96 Å] and were refined using a riding model, with Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating group model was applied to the methyl groups. The F atoms of both anions are disordered over two positions, with site occupancies of 0.50 (3) and 0.50 (3) in one of the anions, and 0.756 (9) and 0.244 (9) in the other anion. In each anion, the C—F distances were restrained to be equal and the Uij components of F atoms were restrained to an approximate isotropic behaviour.
Data collection: APEX2 (Bruker, 2009); cell
SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 30% probability level. All disorder components are shown. | |
Fig. 2. The crystal packing of the title compound, showing the hydrogen-bonded (dashed lines) network. |
C6H9N2+·C2F3O2− | Z = 4 |
Mr = 222.17 | F(000) = 456 |
Triclinic, P1 | Dx = 1.467 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.5229 (2) Å | Cell parameters from 4908 reflections |
b = 11.0649 (3) Å | θ = 2.6–30.0° |
c = 11.6573 (3) Å | µ = 0.14 mm−1 |
α = 81.208 (1)° | T = 296 K |
β = 72.199 (2)° | Plate, colourless |
γ = 74.647 (1)° | 0.56 × 0.19 × 0.08 mm |
V = 1006.26 (4) Å3 |
Bruker SMART APEXII CCD area-detector diffractometer | 5803 independent reflections |
Radiation source: fine-focus sealed tube | 3405 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.028 |
ϕ and ω scans | θmax = 30.0°, θmin = 1.8° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −11→11 |
Tmin = 0.925, Tmax = 0.989 | k = −15→15 |
21533 measured reflections | l = −16→16 |
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)] = 0.070 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.187 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0642P)2 + 0.3844P] where P = (Fo2 + 2Fc2)/3 |
5803 reflections | (Δ/σ)max = 0.001 |
357 parameters | Δρmax = 0.25 e Å−3 |
114 restraints | Δρmin = −0.26 e Å−3 |
C6H9N2+·C2F3O2− | γ = 74.647 (1)° |
Mr = 222.17 | V = 1006.26 (4) Å3 |
Triclinic, P1 | Z = 4 |
a = 8.5229 (2) Å | Mo Kα radiation |
b = 11.0649 (3) Å | µ = 0.14 mm−1 |
c = 11.6573 (3) Å | T = 296 K |
α = 81.208 (1)° | 0.56 × 0.19 × 0.08 mm |
β = 72.199 (2)° |
Bruker SMART APEXII CCD area-detector diffractometer | 5803 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 3405 reflections with I > 2σ(I) |
Tmin = 0.925, Tmax = 0.989 | Rint = 0.028 |
21533 measured reflections |
R[F2 > 2σ(F2)] = 0.070 | 114 restraints |
wR(F2) = 0.187 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.25 e Å−3 |
5803 reflections | Δρmin = −0.26 e Å−3 |
357 parameters |
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 cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
N1A | 0.3581 (3) | 0.99313 (18) | 0.21338 (18) | 0.0510 (5) | |
N2A | 0.2610 (3) | 0.8369 (2) | 0.1674 (2) | 0.0672 (6) | |
C1A | 0.4811 (3) | 1.0518 (2) | 0.2081 (2) | 0.0589 (6) | |
H1AA | 0.4538 | 1.1237 | 0.2490 | 0.071* | |
C2A | 0.6422 (3) | 1.0074 (3) | 0.1447 (2) | 0.0605 (6) | |
H2AA | 0.7258 | 1.0485 | 0.1412 | 0.073* | |
C3A | 0.6831 (3) | 0.8980 (2) | 0.0835 (2) | 0.0553 (6) | |
C4A | 0.5572 (3) | 0.8401 (2) | 0.0901 (2) | 0.0548 (6) | |
H4AA | 0.5829 | 0.7678 | 0.0500 | 0.066* | |
C5A | 0.3900 (3) | 0.8882 (2) | 0.1564 (2) | 0.0500 (6) | |
C6A | 0.8627 (4) | 0.8466 (3) | 0.0138 (3) | 0.0779 (8) | |
H6AA | 0.8721 | 0.7662 | −0.0125 | 0.117* | |
H6AB | 0.9358 | 0.8373 | 0.0645 | 0.117* | |
H6AC | 0.8951 | 0.9033 | −0.0554 | 0.117* | |
N1B | 0.2268 (3) | 0.49192 (19) | 0.32553 (19) | 0.0529 (5) | |
N2B | 0.1215 (4) | 0.3395 (2) | 0.2805 (2) | 0.0708 (7) | |
C1B | 0.2776 (3) | 0.5451 (3) | 0.4013 (2) | 0.0600 (7) | |
H1BB | 0.309 (4) | 0.622 (3) | 0.367 (3) | 0.072 (8)* | |
C2B | 0.2732 (3) | 0.4938 (3) | 0.5135 (3) | 0.0634 (7) | |
H2BA | 0.3074 | 0.5315 | 0.5648 | 0.076* | |
C3B | 0.2162 (3) | 0.3817 (3) | 0.5533 (2) | 0.0612 (6) | |
C4B | 0.1643 (3) | 0.3302 (2) | 0.4769 (2) | 0.0581 (6) | |
H4BA | 0.1248 | 0.2572 | 0.5027 | 0.070* | |
C5B | 0.1695 (3) | 0.3855 (2) | 0.3598 (2) | 0.0508 (6) | |
C6B | 0.2136 (6) | 0.3216 (4) | 0.6779 (3) | 0.0997 (12) | |
H6BA | 0.1825 | 0.2426 | 0.6877 | 0.149* | |
H6BB | 0.1326 | 0.3759 | 0.7365 | 0.149* | |
H6BC | 0.3240 | 0.3079 | 0.6894 | 0.149* | |
F1A | 0.7612 (16) | 0.1532 (10) | 0.5327 (7) | 0.084 (2) | 0.50 (3) |
F2A | 0.6477 (14) | 0.1650 (13) | 0.3757 (10) | 0.102 (3) | 0.50 (3) |
F3A | 0.6788 (15) | 0.0165 (9) | 0.5069 (8) | 0.093 (3) | 0.50 (3) |
F1C | 0.7539 (17) | 0.1841 (16) | 0.5129 (13) | 0.110 (4) | 0.50 (3) |
F2C | 0.6745 (18) | 0.2046 (15) | 0.3790 (11) | 0.122 (4) | 0.50 (3) |
F3C | 0.6439 (18) | 0.0349 (13) | 0.4851 (15) | 0.117 (4) | 0.50 (3) |
O1A | 0.9324 (3) | −0.0511 (2) | 0.3165 (2) | 0.0937 (7) | |
O2A | 1.0382 (2) | 0.10073 (17) | 0.34606 (19) | 0.0712 (6) | |
C7A | 0.9242 (3) | 0.0450 (2) | 0.3593 (2) | 0.0562 (6) | |
C8A | 0.7515 (3) | 0.1063 (3) | 0.4389 (2) | 0.0636 (7) | |
F1B | 0.4287 (6) | 0.6567 (4) | 0.8679 (3) | 0.0917 (13) | 0.756 (9) |
F2B | 0.1802 (5) | 0.6740 (7) | 0.8575 (4) | 0.136 (2) | 0.756 (9) |
F3B | 0.3737 (6) | 0.5082 (4) | 0.8111 (4) | 0.1062 (14) | 0.756 (9) |
F1D | 0.310 (2) | 0.7120 (8) | 0.8858 (9) | 0.101 (4) | 0.244 (9) |
F2D | 0.1842 (14) | 0.6008 (13) | 0.8405 (11) | 0.094 (4) | 0.244 (9) |
F3D | 0.4324 (15) | 0.5237 (15) | 0.8247 (14) | 0.122 (5) | 0.244 (9) |
O1B | 0.2191 (3) | 0.4371 (2) | 1.03426 (19) | 0.0899 (7) | |
O2B | 0.2503 (3) | 0.60549 (17) | 1.09745 (16) | 0.0786 (6) | |
C7B | 0.2531 (3) | 0.5397 (2) | 1.0201 (2) | 0.0566 (6) | |
C8B | 0.3048 (3) | 0.5954 (3) | 0.8898 (2) | 0.0649 (7) | |
H1NA | 0.252 (4) | 1.022 (2) | 0.257 (2) | 0.057 (7)* | |
H2NA | 0.161 (3) | 0.869 (2) | 0.209 (2) | 0.062 (8)* | |
H3NA | 0.276 (4) | 0.775 (2) | 0.127 (2) | 0.077 (9)* | |
H1NB | 0.238 (3) | 0.524 (2) | 0.251 (3) | 0.058 (7)* | |
H2NB | 0.146 (4) | 0.368 (3) | 0.2065 (19) | 0.079 (10)* | |
H3NB | 0.078 (3) | 0.278 (2) | 0.301 (3) | 0.070 (9)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1A | 0.0562 (13) | 0.0494 (11) | 0.0466 (11) | −0.0169 (9) | −0.0063 (10) | −0.0099 (8) |
N2A | 0.0761 (17) | 0.0585 (14) | 0.0704 (15) | −0.0299 (13) | −0.0057 (13) | −0.0204 (12) |
C1A | 0.0699 (17) | 0.0555 (14) | 0.0587 (15) | −0.0232 (13) | −0.0167 (13) | −0.0136 (11) |
C2A | 0.0599 (16) | 0.0667 (16) | 0.0606 (15) | −0.0210 (13) | −0.0189 (13) | −0.0064 (12) |
C3A | 0.0599 (15) | 0.0566 (14) | 0.0451 (13) | −0.0056 (12) | −0.0168 (11) | −0.0005 (10) |
C4A | 0.0710 (16) | 0.0439 (12) | 0.0463 (13) | −0.0077 (11) | −0.0160 (12) | −0.0049 (10) |
C5A | 0.0684 (16) | 0.0418 (11) | 0.0407 (11) | −0.0174 (11) | −0.0143 (11) | 0.0007 (9) |
C6A | 0.0636 (18) | 0.084 (2) | 0.076 (2) | −0.0031 (15) | −0.0145 (15) | −0.0103 (16) |
N1B | 0.0631 (13) | 0.0487 (11) | 0.0455 (11) | −0.0230 (10) | −0.0047 (10) | −0.0029 (9) |
N2B | 0.0989 (19) | 0.0645 (15) | 0.0620 (15) | −0.0456 (14) | −0.0189 (14) | −0.0039 (12) |
C1B | 0.0676 (17) | 0.0579 (15) | 0.0575 (15) | −0.0305 (13) | −0.0076 (12) | −0.0056 (12) |
C2B | 0.0653 (16) | 0.0714 (17) | 0.0621 (16) | −0.0281 (14) | −0.0186 (13) | −0.0066 (13) |
C3B | 0.0603 (15) | 0.0629 (15) | 0.0607 (15) | −0.0179 (12) | −0.0191 (12) | 0.0055 (12) |
C4B | 0.0627 (15) | 0.0490 (13) | 0.0619 (15) | −0.0228 (12) | −0.0122 (12) | 0.0048 (11) |
C5B | 0.0505 (13) | 0.0451 (12) | 0.0545 (14) | −0.0159 (10) | −0.0054 (10) | −0.0068 (10) |
C6B | 0.140 (3) | 0.101 (3) | 0.079 (2) | −0.054 (2) | −0.058 (2) | 0.0303 (19) |
F1A | 0.096 (4) | 0.091 (4) | 0.054 (3) | −0.014 (3) | −0.010 (2) | −0.012 (3) |
F2A | 0.083 (4) | 0.122 (5) | 0.092 (4) | 0.007 (4) | −0.037 (3) | −0.012 (4) |
F3A | 0.076 (4) | 0.117 (4) | 0.073 (4) | −0.038 (3) | 0.000 (3) | 0.015 (3) |
F1C | 0.101 (5) | 0.114 (6) | 0.127 (6) | −0.038 (4) | −0.010 (4) | −0.068 (5) |
F2C | 0.100 (5) | 0.125 (6) | 0.103 (5) | 0.013 (4) | −0.025 (3) | 0.023 (4) |
F3C | 0.080 (4) | 0.131 (6) | 0.146 (7) | −0.068 (4) | 0.001 (4) | −0.024 (4) |
O1A | 0.0789 (14) | 0.0947 (16) | 0.1201 (19) | −0.0387 (12) | −0.0099 (13) | −0.0498 (14) |
O2A | 0.0621 (11) | 0.0612 (11) | 0.0907 (14) | −0.0314 (9) | −0.0031 (10) | −0.0147 (10) |
C7A | 0.0600 (15) | 0.0598 (14) | 0.0554 (14) | −0.0271 (12) | −0.0143 (12) | −0.0044 (11) |
C8A | 0.0613 (16) | 0.0771 (19) | 0.0573 (16) | −0.0277 (14) | −0.0137 (13) | −0.0049 (13) |
F1B | 0.098 (3) | 0.100 (2) | 0.0800 (17) | −0.053 (2) | −0.0076 (16) | 0.0035 (15) |
F2B | 0.086 (2) | 0.174 (4) | 0.093 (2) | 0.023 (3) | −0.0136 (18) | 0.040 (3) |
F3B | 0.119 (3) | 0.130 (3) | 0.0665 (18) | −0.051 (2) | 0.0142 (19) | −0.0440 (16) |
F1D | 0.146 (8) | 0.084 (5) | 0.079 (5) | −0.052 (5) | −0.025 (5) | 0.008 (4) |
F2D | 0.105 (6) | 0.113 (7) | 0.084 (5) | −0.030 (5) | −0.062 (5) | 0.012 (5) |
F3D | 0.078 (6) | 0.148 (8) | 0.112 (7) | −0.006 (5) | −0.002 (5) | −0.010 (6) |
O1B | 0.140 (2) | 0.0703 (13) | 0.0708 (13) | −0.0528 (14) | −0.0189 (13) | −0.0111 (10) |
O2B | 0.1372 (19) | 0.0565 (11) | 0.0532 (11) | −0.0412 (12) | −0.0259 (11) | −0.0054 (8) |
C7B | 0.0670 (16) | 0.0506 (13) | 0.0537 (14) | −0.0165 (12) | −0.0137 (12) | −0.0094 (11) |
C8B | 0.0657 (18) | 0.0713 (18) | 0.0547 (15) | −0.0147 (15) | −0.0106 (13) | −0.0108 (13) |
N1A—C5A | 1.350 (3) | C2B—H2BA | 0.93 |
N1A—C1A | 1.354 (3) | C3B—C4B | 1.356 (4) |
N1A—H1NA | 0.89 (3) | C3B—C6B | 1.499 (4) |
N2A—C5A | 1.330 (3) | C4B—C5B | 1.401 (3) |
N2A—H2NA | 0.855 (18) | C4B—H4BA | 0.93 |
N2A—H3NA | 0.850 (19) | C6B—H6BA | 0.96 |
C1A—C2A | 1.344 (4) | C6B—H6BB | 0.96 |
C1A—H1AA | 0.93 | C6B—H6BC | 0.96 |
C2A—C3A | 1.408 (4) | F1A—C8A | 1.314 (6) |
C2A—H2AA | 0.93 | F2A—C8A | 1.301 (6) |
C3A—C4A | 1.366 (3) | F3A—C8A | 1.336 (6) |
C3A—C6A | 1.499 (4) | F1C—C8A | 1.316 (6) |
C4A—C5A | 1.401 (3) | F2C—C8A | 1.331 (6) |
C4A—H4AA | 0.93 | F3C—C8A | 1.306 (6) |
C6A—H6AA | 0.96 | O1A—C7A | 1.219 (3) |
C6A—H6AB | 0.96 | O2A—C7A | 1.243 (3) |
C6A—H6AC | 0.96 | C7A—C8A | 1.522 (4) |
N1B—C5B | 1.351 (3) | F1B—C8B | 1.343 (4) |
N1B—C1B | 1.356 (3) | F2B—C8B | 1.296 (4) |
N1B—H1NB | 0.88 (3) | F3B—C8B | 1.326 (4) |
N2B—C5B | 1.329 (3) | F1D—C8B | 1.297 (6) |
N2B—H2NB | 0.854 (19) | F2D—C8B | 1.307 (7) |
N2B—H3NB | 0.830 (19) | F3D—C8B | 1.269 (8) |
C1B—C2B | 1.338 (4) | O1B—C7B | 1.220 (3) |
C1B—H1BB | 0.95 (3) | O2B—C7B | 1.233 (3) |
C2B—C3B | 1.412 (4) | C7B—C8B | 1.526 (4) |
C5A—N1A—C1A | 122.3 (2) | C4B—C3B—C2B | 118.8 (2) |
C5A—N1A—H1NA | 116.6 (16) | C4B—C3B—C6B | 121.1 (3) |
C1A—N1A—H1NA | 121.0 (16) | C2B—C3B—C6B | 120.0 (3) |
C5A—N2A—H2NA | 121.2 (18) | C3B—C4B—C5B | 120.9 (2) |
C5A—N2A—H3NA | 119 (2) | C3B—C4B—H4BA | 119.5 |
H2NA—N2A—H3NA | 119 (3) | C5B—C4B—H4BA | 119.5 |
C2A—C1A—N1A | 120.9 (2) | N2B—C5B—N1B | 118.1 (2) |
C2A—C1A—H1AA | 119.5 | N2B—C5B—C4B | 123.9 (2) |
N1A—C1A—H1AA | 119.5 | N1B—C5B—C4B | 118.0 (2) |
C1A—C2A—C3A | 119.3 (2) | C3B—C6B—H6BA | 109.5 |
C1A—C2A—H2AA | 120.3 | C3B—C6B—H6BB | 109.5 |
C3A—C2A—H2AA | 120.3 | H6BA—C6B—H6BB | 109.5 |
C4A—C3A—C2A | 118.9 (2) | C3B—C6B—H6BC | 109.5 |
C4A—C3A—C6A | 121.2 (2) | H6BA—C6B—H6BC | 109.5 |
C2A—C3A—C6A | 119.9 (3) | H6BB—C6B—H6BC | 109.5 |
C3A—C4A—C5A | 120.8 (2) | O1A—C7A—O2A | 128.6 (3) |
C3A—C4A—H4AA | 119.6 | O1A—C7A—C8A | 116.2 (2) |
C5A—C4A—H4AA | 119.6 | O2A—C7A—C8A | 115.2 (2) |
N2A—C5A—N1A | 117.9 (2) | F2A—C8A—F1A | 122.3 (9) |
N2A—C5A—C4A | 124.3 (2) | F3C—C8A—F1C | 114.7 (11) |
N1A—C5A—C4A | 117.7 (2) | F3C—C8A—F2C | 106.7 (7) |
C3A—C6A—H6AA | 109.5 | F1C—C8A—F2C | 88.3 (16) |
C3A—C6A—H6AB | 109.5 | F2A—C8A—F3A | 104.7 (7) |
H6AA—C6A—H6AB | 109.5 | F1A—C8A—F3A | 93.2 (7) |
C3A—C6A—H6AC | 109.5 | F2A—C8A—C7A | 112.1 (6) |
H6AA—C6A—H6AC | 109.5 | F1A—C8A—C7A | 112.8 (6) |
H6AB—C6A—H6AC | 109.5 | F3A—C8A—C7A | 108.9 (5) |
C5B—N1B—C1B | 121.7 (2) | O1B—C7B—O2B | 128.6 (3) |
C5B—N1B—H1NB | 118.8 (17) | O1B—C7B—C8B | 116.2 (2) |
C1B—N1B—H1NB | 119.3 (16) | O2B—C7B—C8B | 115.2 (2) |
C5B—N2B—H2NB | 120 (2) | F3D—C8B—F1D | 116.9 (9) |
C5B—N2B—H3NB | 120 (2) | F3D—C8B—F2D | 103.4 (9) |
H2NB—N2B—H3NB | 120 (3) | F1D—C8B—F2D | 103.7 (7) |
C2B—C1B—N1B | 121.1 (2) | F2B—C8B—F3B | 108.5 (4) |
C2B—C1B—H1BB | 125.9 (17) | F2B—C8B—F1B | 106.5 (4) |
N1B—C1B—H1BB | 112.9 (17) | F3B—C8B—F1B | 101.8 (3) |
C1B—C2B—C3B | 119.4 (2) | F2B—C8B—C7B | 113.0 (3) |
C1B—C2B—H2BA | 120.3 | F3B—C8B—C7B | 112.8 (3) |
C3B—C2B—H2BA | 120.3 | F1B—C8B—C7B | 113.5 (2) |
C5A—N1A—C1A—C2A | 0.2 (4) | O1A—C7A—C8A—F3C | 20.8 (11) |
N1A—C1A—C2A—C3A | −0.3 (4) | O2A—C7A—C8A—F3C | −159.7 (11) |
C1A—C2A—C3A—C4A | 0.2 (4) | O1A—C7A—C8A—F1A | 141.7 (6) |
C1A—C2A—C3A—C6A | −179.2 (3) | O2A—C7A—C8A—F1A | −38.8 (6) |
C2A—C3A—C4A—C5A | 0.0 (4) | O1A—C7A—C8A—F1C | 159.8 (10) |
C6A—C3A—C4A—C5A | 179.4 (2) | O2A—C7A—C8A—F1C | −20.6 (10) |
C1A—N1A—C5A—N2A | 179.6 (2) | O1A—C7A—C8A—F2C | −101.8 (11) |
C1A—N1A—C5A—C4A | 0.0 (3) | O2A—C7A—C8A—F2C | 77.7 (11) |
C3A—C4A—C5A—N2A | −179.7 (2) | O1A—C7A—C8A—F3A | 39.7 (6) |
C3A—C4A—C5A—N1A | −0.1 (3) | O2A—C7A—C8A—F3A | −140.8 (6) |
C5B—N1B—C1B—C2B | 0.1 (4) | O1B—C7B—C8B—F3D | −57.7 (10) |
N1B—C1B—C2B—C3B | 0.6 (4) | O2B—C7B—C8B—F3D | 122.7 (10) |
C1B—C2B—C3B—C4B | −1.2 (4) | O1B—C7B—C8B—F2B | 96.6 (5) |
C1B—C2B—C3B—C6B | 178.8 (3) | O2B—C7B—C8B—F2B | −83.0 (5) |
C2B—C3B—C4B—C5B | 1.1 (4) | O1B—C7B—C8B—F1D | 169.3 (10) |
C6B—C3B—C4B—C5B | −179.0 (3) | O2B—C7B—C8B—F1D | −10.3 (10) |
C1B—N1B—C5B—N2B | 179.7 (3) | O1B—C7B—C8B—F2D | 55.9 (8) |
C1B—N1B—C5B—C4B | −0.3 (4) | O2B—C7B—C8B—F2D | −123.7 (7) |
C3B—C4B—C5B—N2B | 179.6 (3) | O1B—C7B—C8B—F3B | −26.9 (4) |
C3B—C4B—C5B—N1B | −0.3 (4) | O2B—C7B—C8B—F3B | 153.5 (3) |
O1A—C7A—C8A—F2A | −75.6 (8) | O1B—C7B—C8B—F1B | −142.0 (3) |
O2A—C7A—C8A—F2A | 103.9 (8) | O2B—C7B—C8B—F1B | 38.4 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1NA···O2Ai | 0.89 (3) | 1.85 (3) | 2.740 (3) | 173 (2) |
N2A—H2NA···O1Ai | 0.85 (2) | 2.02 (2) | 2.871 (3) | 176 (2) |
N2A—H3NA···O2Bii | 0.85 (2) | 2.04 (2) | 2.835 (3) | 156 (2) |
N1B—H1NB···O2Bii | 0.87 (3) | 1.86 (3) | 2.734 (3) | 175 (2) |
N2B—H2NB···O1Bii | 0.85 (2) | 2.01 (2) | 2.858 (3) | 176 (3) |
N2B—H3NB···O2Aiii | 0.83 (3) | 2.04 (2) | 2.848 (3) | 164 (3) |
C4A—H4AA···O1Biv | 0.93 | 2.57 | 3.423 (3) | 153 |
C6B—H6BA···O1Av | 0.96 | 2.57 | 3.518 (5) | 169 |
Symmetry codes: (i) x−1, y+1, z; (ii) x, y, z−1; (iii) x−1, y, z; (iv) −x+1, −y+1, −z+1; (v) −x+1, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C6H9N2+·C2F3O2− |
Mr | 222.17 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 8.5229 (2), 11.0649 (3), 11.6573 (3) |
α, β, γ (°) | 81.208 (1), 72.199 (2), 74.647 (1) |
V (Å3) | 1006.26 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.14 |
Crystal size (mm) | 0.56 × 0.19 × 0.08 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.925, 0.989 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 21533, 5803, 3405 |
Rint | 0.028 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.070, 0.187, 1.06 |
No. of reflections | 5803 |
No. of parameters | 357 |
No. of restraints | 114 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.25, −0.26 |
Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1NA···O2Ai | 0.89 (3) | 1.85 (3) | 2.740 (3) | 173 (2) |
N2A—H2NA···O1Ai | 0.85 (2) | 2.02 (2) | 2.871 (3) | 176 (2) |
N2A—H3NA···O2Bii | 0.85 (2) | 2.04 (2) | 2.835 (3) | 156 (2) |
N1B—H1NB···O2Bii | 0.87 (3) | 1.86 (3) | 2.734 (3) | 175 (2) |
N2B—H2NB···O1Bii | 0.85 (2) | 2.01 (2) | 2.858 (3) | 176 (3) |
N2B—H3NB···O2Aiii | 0.83 (3) | 2.04 (2) | 2.848 (3) | 164 (3) |
C4A—H4AA···O1Biv | 0.93 | 2.57 | 3.423 (3) | 153 |
C6B—H6BA···O1Av | 0.96 | 2.57 | 3.518 (5) | 169 |
Symmetry codes: (i) x−1, y+1, z; (ii) x, y, z−1; (iii) x−1, y, z; (iv) −x+1, −y+1, −z+1; (v) −x+1, −y, −z+1. |
Footnotes
‡Thomson Reuters ResearcherID: A-3561-2009.
Acknowledgements
MH and HKF thank the Malaysian Government and Universiti Sains Malaysia (USM) for the Research University Golden Goose grant No. 1001/PFIZIK/811012. MH thanks USM for a post-doctoral research fellowship.
References
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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.
Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996). They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). Trifluoroacetic acid (TFA) is a very strong carboxylic acid, easily volatile, and used for protein purifications. Several trifluoroacetate salts and their crystal structures have been reported (Rodrigues et al., 2001). The crystal structures of 2-amino-4-methylpyridine (Kvick & Noordik, 1977), 2-amino-4-methylpyridinium 4-aminobenzoate (Shen et al., 2008) have also been reported. We have recently reported the crystal structure of 2-amino-4-methylpyridinium 4-nitrobenzoate (Hemamalini & Fun, 2010). In continuation of our studies of pyridinium derivatives, the crystal structure determination of the title compound has been undertaken.
The asymmetric unit of the title compound consists of two crystallographically independent 2-amino-4-methylpyridinium cations (A and B) and two trifluoroacetate anions (A and B) (Fig. 1). Each 2-amino-4-methylpyridinium cation is planar, with a maximum deviation of 0.007 (3) Å for atom C6A in cation A and 0.011 (5) Å for atom C6B in cation B. The protonation of atoms N1A and N1B lead to a slight increase in C1A—N1A—C5A [122.3 (2)°] and C1B—N1B—C5B [121.7 (2)°] angles.
In the crystal packing (Fig. 2), the A (and B)-type 2-amino-4-methylpyridinium cations interact with the carboxylate groups of A (and B)-type trifluoroacetate anions through a pair of N—H···O hydrogen bonds, forming an R22(8) motif (Bernstein et al., 1995). The cation-anion pairs are linked into a chain along the b axis by N—H···O hydrogen bonds. The crystal structure is further stabilized by C—H···O (Table 1) hydrogen bonds and π–π interactions involving the N1A/C1A–C5A and N1A/C1A–C5A pyridine rings [centoid-to-centroid separation = 3.5842 (13) Å], and N1B/C1B–C5B and N1B/C1B–C5B rings [centoid-to-centroid separation = 3.5665 (16) Å].