3-Pyridin-2-yl-1H-1,2,4-triazol-5-amine

Anton V Dolzhenko; Geok Kheng Tan; Lip Lin Koh; Anna V Dolzhenko; Wai Keung Chui

doi:10.1107/S1600536808042177

. 2008 Dec 17;65(Pt 1):o125. doi: 10.1107/S1600536808042177

3-Pyridin-2-yl-1H-1,2,4-triazol-5-amine

Anton V Dolzhenko ^a,^*, Geok Kheng Tan ^b, Lip Lin Koh ^b, Anna V Dolzhenko ^a, Wai Keung Chui ^a

PMCID: PMC2968045 PMID: 21581586

Abstract

In the title compound, C₇H₇N₅, the non-H atoms are almost coplanar (r.m.s. deviation = 0.050 Å), with the N atom of pyridine ring oriented to the N—N(H) side of the 1,2,4-triazole ring. The mean planes of the pyridine and 1,2,4-triazole rings form a dihedral angle of 5.58 (7)°. The N atom of the amino group adopts a pyramidal configuration. The molecules are linked into a two-dimensional network parallel to (10 Inline graphic ) by N—H⋯N hydrogen bonds.

Related literature

For 1,2,4-triazol-5-amines as building blocks in the synthesis of fused heterocyclic systems, see: Dolzhenko et al. (2006 ▶, 2007a ▶,b ▶); Fischer, (2007 ▶). For a summary of structural data for 1,2,4-triazoles, see: Buzykin et al. (2006 ▶). For crystal structures of Cu^II complexes with 3-pyridin-2-yl-1,2,4-triazol-5-amine, see: Ferrer et al. (2004 ▶).

Experimental

Crystal data

C₇H₇N₅
M _r = 161.18
Monoclinic,
a = 7.3863 (6) Å
b = 7.9096 (6) Å
c = 13.2157 (11) Å
β = 91.832 (2)°
V = 771.70 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 223 (2) K
0.36 × 0.16 × 0.12 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ▶) T _min = 0.967, T _max = 0.989
5336 measured reflections
1772 independent reflections
1519 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.110
S = 1.05
1772 reflections
121 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808042177/ci2719sup1.cif

e-65-0o125-sup1.cif^{(13.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808042177/ci2719Isup2.hkl

e-65-0o125-Isup2.hkl^{(87.3KB, 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
N2—H2N⋯N5ⁱ	0.90 (2)	2.01 (2)	2.9010 (16)	171 (1)
N4—H4A⋯N3ⁱⁱ	0.90 (2)	2.11 (2)	2.9971 (16)	172 (1)
N4—H4B⋯N1ⁱ	0.93 (2)	2.19 (2)	3.0264 (16)	151 (1)

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

Acknowledgments

This work was supported by the National Medical Research Council, Singapore (grant Nos. NMRC/NIG/0019/2008 and NMRC/NIG/0020/2008).

supplementary crystallographic information

Comment

1,2,4-Triazol-5-amines have been recognized as valuable synthons for the construction of fused heterocyclic systems, e.g. 1,2,4-triazolo[1,5-a]pyrimidines (Fischer, 2007) and 1,2,4-triazolo[1,5-a][1,3,5]triazines (Dolzhenko et al., 2006). It also should be mentioned that 1,2,4-triazol-5-amines are widely used as ligands and crystallographic data on three different mononuclear complexes of 3-pyridin-2-yl-1,2,4-triazol-5-amine with Cu^II have been reported by Ferrer et al. (2004). However, no crystallographic study has been performed on the ligand.

In continuation of our investigations on using 1,2,4-triazol-5-amines in the synthesis of fused heterocyclic systems (Dolzhenko et al., 2007a,b), we report herein the crystal structure of a synthetically important building block viz. 3-pyridin-2-yl-1,2,4-triazol-5-amine.

Due to annular tautomerism, 3-pyridin-2-yl-1,2,4-triazol-5-amine may theoretically exist in three tautomeric forms (A, B and C) and for each of them, rotameric structures A', B' and C' are possible (Fig.1). As observed in reported Cu^II complexes (Ferrer et al., 2004), 3-pyridin-2-yl-1,2,4-triazol-5-amine was the only tautomeric form found in the crystal (Fig. 2). However, the molecule exists in the crystal as rotamer A in contrast to rotamer A' found in Cu^II complexes.

Bond lengths and angles in the molecule of 3-pyridin-2-yl-1,2,4-triazol-5-amine are within normal ranges, and comparable with values summarized for 1,2,4-triazoles by Buzykin et al. (2006). 3-Pyridin-2-yl-1,2,4-triazol-5-amine has practically planar geometry with slight deviation of the pyridyl moiety, which makes a dihedral angle of 5.58 (7)° with mean plane of the 1,2,4-triazole ring. The nitrogen atom (N4) of the amino group adopts a pyramidal configuration with 0.26 (2) Å deviation of the nitrogen atom from the C2/H4A/H4B plane.

The molecules are linked into a two-dimensional network parallel to the (101) by N—H···N hydrogen bonds (Table 1 and Fig.3).

Experimental

3-Pyridin-2-yl-1,2,4-triazol-5-amine was prepared according to general method reported by Dolzhenko et al. (2007a,b). Single crystals suitable for crystallographic analysis were grown by recrystallization from ethanol.