3-Amino-1-methyl­pyrazin-1-ium chloride

Daniel Foucher; Stephen Wylie; Joshua Acosta; Alan J Lough

doi:10.1107/S1600536809051265

. 2009 Dec 4;66(Pt 1):o61. doi: 10.1107/S1600536809051265

3-Amino-1-methylpyrazin-1-ium chloride

Daniel Foucher ^a, Stephen Wylie ^a, Joshua Acosta ^a, Alan J Lough ^b,^*

PMCID: PMC2980274 PMID: 21580163

Abstract

In the cation of the title compound, C₅H₈N₃ ⁺·Cl⁻, the C—N(H₂) bond distance [1.348 (3) Å] is at the lower end of the range for aryl amines. In the crystal structure, cations and anions are linked via N—H⋯Cl hydrogen bonds, forming one-dimensional chains along [100].

Related literature

For the synthesis and characterization of the title compound, see: Foucher et al. (1993 ▶). Additional preparative details of similar compounds are given by Goto et al. (1968 ▶). For related structures, see Chao et al. (1976 ▶); Kazheva et al. (2006 ▶); Foucher et al. (1989 ▶); Lu & Xi (2008 ▶). For the crystal structure of 3-amino-1- methylpyrazin-1-ium iodide, see: Foucher et al. (2009 ▶). For comparative bond-distance data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₅H₈N₃ ⁺·Cl⁻
M _r = 145.59
Orthorhombic,
a = 11.3164 (3) Å
b = 9.5029 (5) Å
c = 12.3877 (5) Å
V = 1332.16 (10) Å³
Z = 8
Mo Kα radiation
μ = 0.48 mm⁻¹
T = 150 K
0.24 × 0.16 × 0.12 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing 1995 ▶) T _min = 0.819, T _max = 0.946
9107 measured reflections
1526 independent reflections
1144 reflections with I > 2σ(I)
R _int = 0.047

Refinement

R[F ² > 2σ(F ²)] = 0.040
wR(F ²) = 0.111
S = 1.10
1526 reflections
91 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.46 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Data collection: COLLECT (Nonius BV, 2002 ▶); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO-SMN; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXTL (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809051265/tk2586sup1.cif

e-66-00o61-sup1.cif^{(13.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809051265/tk2586Isup2.hkl

e-66-00o61-Isup2.hkl^{(75.4KB, hkl)}

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
N7—H1N⋯Cl1	0.91 (3)	2.40 (3)	3.297 (2)	168 (2)
N7—H2N⋯Cl1ⁱ	0.94 (3)	2.37 (3)	3.289 (2)	168 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors acknowledge NSERC Canada, the University of Toronto and the Dean’s Seed Fund Initiative (Ryerson University) for funding.

supplementary crystallographic information

Comment

The title chloride compound, (I), was recovered from the ion exchange (Dowex 1-X8 ion exchange resin saturated with Cl^- anions) of the iodide precursor of N-methyl-3-aminopyrazinium iodide (Foucher et al., 1993). The proximity of the amine group to one of the diazine N atoms makes it an ideal chelating ligand to metals and geometrically suggests the possibility for amine-imine tautomerism. We have investigated the possibility that a smaller counter ion might induce a preference for the imine tautomer in these salts.

The molecular structure of (I) is shown in Fig. 1. The cation is the amine tautomer and resembles closely in terms of bond angles and bond lengths, other N-methylated amino pyrazinium salts (Kazheva et al., 2006; Foucher et al., 1989). The C5—N4—C3 bond angle in (I) [121.02 (18) °] is significantly wider than in 2-aminopyrazine [116.6 (1)°] (Chao et al., 1976) but similar to the angle found in N-methyl-3-aminopyrazinium iodide (121.3 (5)°; Foucher et al., 2010). 2-Aminopyrazine and both N-methyl-3-aminopyrazium salts are characterized by short amine-ring bond distances [N7—C6 in (I) = 1.348 (3) Å, 1.341 (1)Å (Chao et al., 1976) and 1.338 (8)Å (Foucher et al., 2009)] compared to typical values for C(sp²)-NH₂ bond lengths, i.e. 1.36 Å (Allen et al., 1987)] although these distances are significantly longer than the C=N(H) bond [1.285 (4) Å] in N-(4-imino-3,5-dimethylcyclohexa-2,5-dienylidene)-2,6-dimethylaniline (Lu & Xi, 2008). These short bond lengths are suggestive of a considerable degree of double bond character, where the lone pair of the amine participates in the resonance of the ring π system. In the crystal structure, cations and anions are linked via intermolecular N—H···Cl hydrogen bonds to form one-dimensional chains along [100], Table 1 and Fig. 2.

Experimental

General procedures for the synthesis of this type of compound are given by Goto et al. (1968) and Kazheva et al. (2006). The title compound was recovered from the ion exchange (Dowex 1-X8 ion exchange resin saturated with Cl^- anion) of a concentrated aqueous solution containing 0.30 g (1.266 mmol) of N-methyl-3-pyrazinium iodide (Foucher et al., 1993). The aqueous fractions containing the crude title compound were collected and brought to dryness. Crystals suitable for X-ray diffraction were isolated from the recrystallization of the crude product from boiling ethanol. Yield 0.11 g, 78%. Characterization by NMR agreed with previous literature (Foucher et al., 1993).