2-Amino-5-methyl­pyridinium trifluoro­acetate

Kaliyaperumal Thanigaimani; Abbas Farhadikoutenaei; Nuridayanti Che Khalib; Suhana Arshad; Ibrahim Abdul Razak

doi:10.1107/S1600536812045291

. 2012 Nov 10;68(Pt 12):o3319–o3320. doi: 10.1107/S1600536812045291

2-Amino-5-methylpyridinium trifluoroacetate

Kaliyaperumal Thanigaimani ^a, Abbas Farhadikoutenaei ^a, Nuridayanti Che Khalib ^a, Suhana Arshad ^a, Ibrahim Abdul Razak ^a,^*,^‡

PMCID: PMC3588927 PMID: 23476163

Abstract

In the title salt, C₆H₉N₂ ⁺·C₂F₃O₂ ⁻, the F atoms of the anion are disordered over two sets of sites, with refined occupancies in a ratio of 0.505 (17):0.495 (17). In the crystal, cations and anions are linked via N—H⋯O hydrogen bonds, forming R ₂ ²(8) ring motifs. The ionic units are linked into a two-dimensional network parallel to (100) by N—H⋯O and weak C—H⋯O hydrogen bonds. The crystal structure is further stabilized by weak C—H⋯F hydrogen bonds, resulting in a three-dimensional network.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶). For details of hydrogen bonding, see: Jeffrey & Saenger (1991 ▶); Jeffrey (1997 ▶); Scheiner (1997 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For standard bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶). For a related structure, see: Rodrigues et al. (2001 ▶). graphic file with name e-68-o3319-scheme1.jpg

Experimental

Crystal data

C₆H₉N₂ ⁺·C₂F₃O₂ ⁻
M _r = 222.17
Orthorhombic,
a = 18.725 (4) Å
b = 4.6256 (10) Å
c = 11.319 (2) Å
V = 980.4 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.15 mm⁻¹
T = 100 K
0.54 × 0.29 × 0.11 mm

Data collection

Bruker SMART APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.926, T _max = 0.985
12012 measured reflections
3216 independent reflections
2627 reflections with I > 2σ(I)
R _int = 0.041

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.114
S = 1.07
3216 reflections
177 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.30 e Å⁻³
Absolute structure: Flack (1983 ▶), 1368 Friedel pairs
Flack parameter: −0.1 (7)

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 ▶).

Supplementary Material

Click here for additional data file.^{(21.5KB, cif)}

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812045291/lh5549sup1.cif

e-68-o3319-sup1.cif^{(21.5KB, cif)}

Click here for additional data file.^{(157.8KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812045291/lh5549Isup2.hkl

e-68-o3319-Isup2.hkl^{(157.8KB, hkl)}

Click here for additional data file.^{(3.9KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812045291/lh5549Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N1⋯O2	0.98 (3)	1.75 (3)	2.7281 (19)	177 (2)
N2—H2N2⋯O1	0.95 (3)	1.92 (3)	2.865 (2)	173 (2)
N2—H1N2⋯O2ⁱ	0.86 (3)	1.99 (3)	2.8347 (18)	167 (3)
C3—H3A⋯F2ⁱⁱ	0.95	2.51	3.429 (6)	164
C5—H5A⋯O1ⁱⁱⁱ	0.95	2.27	3.1910 (19)	162

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The authors thank the Malaysian Government and Universiti Sains Malaysia (USM) for the research facilities and Fundamental Research Grant Scheme (FRGS) No. 203/PFIZIK/6711171 to conduct this work. KT thanks The Academy of Sciences for the Developing World and USM for a TWAS–USM fellowship.

supplementary crystallographic information

Comment

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 is a very strong carboxylic acid, easily volatile, and used for protein purification. An example of a crystal structure of a trifluoroacetate salts has been reported (Rodrigues et al., 2001). In order to study potential hydrogen bonding interactions the crystal structure determination of the title compound (I) was carried out.

The asymmetric unit (Fig. 1) contains one 2-amino-5-methylpyridinium cation and one trifluoroacetate anion. The F atoms of the anion are disordered over two sets of sites, with occupancies of 0.505 (17) and 0.495 (17). In the 2-amino-5-methylpyridinium cation, a wider than normal angle [C1—N1—C5 = 122.77 (14)°] is subtended at the protonated N1 atom. The 2-amino-5-methylpyridinium cation is essentially planar, with a maximum deviation of 0.016 (2) Å for atom N2. The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal (Fig. 2), the cations and anions are linked via N—H···O hydrogen bonds to form R₂²(8) ring motifs (Bernstein et al., 1995). The ionic units are linked into a two-dimensional network parallel to (100) by N2—H1N2···O2ⁱ and C5—H5A···O1ⁱⁱⁱ hydrogen bonds (symmetry codes in Table 1). The crystal structure is further stabilized by C3—H3A···F2ⁱⁱ hydrogen bonds, resulting in a three-dimensional network.

Experimental

To a hot methanol solution (20 ml) of 2-amino-5-methylpyridine (54 mg, Aldrich) was added a few drops of trifluoroacetic acid. The solution was warmed over a heating magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound (I) appeared after a few days.