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Acta Cryst. (2009). E65, o125    [ doi:10.1107/S1600536808042177 ]

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

A. V. Dolzhenko, G. K. Tan, L. L. Koh, A. V. Dolzhenko and W. K. Chui

Abstract top

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\overline{1}) by N-H...N hydrogen bonds.

Comment top

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 CuII 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 CuII 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 CuII 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).

Related literature top

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 in crystals, see: Buzykin et al. (2006). For crystal structures of CuII complexes with 3-pyridin-2-yl-1,2,4-triazol-5-amine, see: Ferrer et al. (2004).

Experimental top

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.

Refinement top

N-bound H-atoms were located in a difference map and refined freely [N—H = 0.90 (2)–0.92 (2) Å]. C-bound H atoms were positioned geometrically (C—H = 0.94 Å) and were constrained in a riding motion approximation with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); 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 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Possible tautomers and rotamers of 3-pyridin-2-yl-1,2,4-triazol-5-amine.
[Figure 2] Fig. 2. The molecular structure of the title compound, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 3] Fig. 3. Molecular packing of the title compound, viewed along the c axis.
3-Pyridin-2-yl-1H-1,2,4-triazol-5-amine top
Crystal data top
C7H7N5F(000) = 336
Mr = 161.18Dx = 1.387 Mg m−3
Monoclinic, P21/nMelting point: 493 K
Hall symbol: -P 2ynMo Kα radiation, λ = 0.71073 Å
a = 7.3863 (6) ÅCell parameters from 1841 reflections
b = 7.9096 (6) Åθ = 3.0–26.6°
c = 13.2157 (11) ŵ = 0.10 mm−1
β = 91.832 (2)°T = 223 K
V = 771.70 (11) Å3Block, colourless
Z = 40.36 × 0.16 × 0.12 mm
Data collection top
Bruker SMART APEX CCD
diffractometer		1772 independent reflections
Radiation source: fine-focus sealed tube1519 reflections with I > 2σ(I)
graphiteRint = 0.026
φ and ω scansθmax = 27.5°, θmin = 3.0°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2001)		h = −9→9
Tmin = 0.967, Tmax = 0.989k = −8→10
5336 measured reflectionsl = −14→17
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.110H atoms treated by a mixture of independent and constrained refinement
S = 1.05 w = 1/[σ2(Fo2) + (0.0539P)2 + 0.1487P]
where P = (Fo2 + 2Fc2)/3
1772 reflections(Δ/σ)max = 0.001
121 parametersΔρmax = 0.21 e Å−3
0 restraintsΔρmin = −0.20 e Å−3
Crystal data top
C7H7N5V = 771.70 (11) Å3
Mr = 161.18Z = 4
Monoclinic, P21/nMo Kα radiation
a = 7.3863 (6) ŵ = 0.10 mm−1
b = 7.9096 (6) ÅT = 223 K
c = 13.2157 (11) Å0.36 × 0.16 × 0.12 mm
β = 91.832 (2)°
Data collection top
Bruker SMART APEX CCD
diffractometer		1772 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2001)		1519 reflections with I > 2σ(I)
Tmin = 0.967, Tmax = 0.989Rint = 0.026
5336 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.042H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.110Δρmax = 0.21 e Å−3
S = 1.05Δρmin = −0.20 e Å−3
1772 reflectionsAbsolute structure: ?
121 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
N10.72741 (16)0.34999 (14)0.68693 (8)0.0383 (3)
N20.66107 (16)0.19639 (15)0.71630 (8)0.0393 (3)
H2N0.669 (2)0.164 (2)0.7817 (14)0.052 (5)*
N30.61324 (14)0.20352 (14)0.55193 (8)0.0345 (3)
N40.51489 (16)−0.04181 (15)0.64256 (9)0.0398 (3)
H4A0.488 (2)−0.095 (2)0.5842 (13)0.049 (4)*
H4B0.564 (2)−0.106 (2)0.6948 (13)0.050 (4)*
N50.80901 (15)0.62905 (15)0.56803 (8)0.0388 (3)
C10.69411 (16)0.34759 (16)0.58805 (9)0.0331 (3)
C20.59494 (16)0.11150 (17)0.63532 (9)0.0343 (3)
C30.74353 (16)0.48955 (17)0.52229 (9)0.0343 (3)
C40.72299 (19)0.47748 (19)0.41755 (10)0.0425 (3)
H40.67580.37860.38730.051*
C50.77288 (19)0.6128 (2)0.35870 (11)0.0491 (4)
H50.75980.60760.28780.059*
C60.8419 (2)0.7554 (2)0.40516 (12)0.0486 (4)
H60.87810.84890.36680.058*
C70.85663 (19)0.75796 (19)0.50930 (12)0.0455 (4)
H70.90290.85610.54080.055*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0476 (6)0.0387 (6)0.0282 (5)−0.0007 (5)−0.0076 (4)0.0006 (4)
N20.0518 (7)0.0392 (6)0.0261 (6)−0.0013 (5)−0.0092 (5)0.0000 (5)
N30.0362 (5)0.0396 (6)0.0273 (5)0.0042 (4)−0.0059 (4)−0.0028 (4)
N40.0498 (7)0.0397 (6)0.0291 (6)−0.0021 (5)−0.0110 (5)−0.0001 (5)
N50.0420 (6)0.0409 (6)0.0332 (6)0.0030 (5)−0.0043 (5)0.0012 (5)
C10.0330 (6)0.0385 (7)0.0273 (6)0.0057 (5)−0.0056 (5)−0.0035 (5)
C20.0357 (6)0.0391 (7)0.0274 (6)0.0053 (5)−0.0068 (5)−0.0030 (5)
C30.0305 (6)0.0419 (7)0.0301 (6)0.0076 (5)−0.0028 (5)−0.0010 (5)
C40.0442 (7)0.0522 (8)0.0310 (7)0.0046 (6)−0.0016 (5)−0.0025 (6)
C50.0488 (8)0.0683 (10)0.0304 (7)0.0080 (7)0.0032 (6)0.0071 (7)
C60.0444 (8)0.0558 (9)0.0457 (8)0.0057 (7)0.0046 (6)0.0150 (7)
C70.0454 (8)0.0447 (8)0.0460 (8)0.0013 (6)−0.0035 (6)0.0050 (6)
Geometric parameters (Å, °) top
N1—C11.3221 (16)N5—C31.3410 (17)
N1—N21.3708 (16)C1—C31.4729 (18)
N2—C21.3422 (16)C3—C41.3909 (18)
N2—H2N0.902 (19)C4—C51.380 (2)
N3—C21.3312 (17)C4—H40.94
N3—C11.3656 (16)C5—C61.374 (2)
N4—C21.3538 (18)C5—H50.94
N4—H4A0.896 (18)C6—C71.377 (2)
N4—H4B0.925 (17)C6—H60.94
N5—C71.3354 (18)C7—H70.94
C1—N1—N2102.14 (10)N5—C3—C4122.10 (13)
C2—N2—N1109.99 (11)N5—C3—C1116.99 (11)
C2—N2—H2N129.2 (11)C4—C3—C1120.91 (12)
N1—N2—H2N120.8 (11)C5—C4—C3119.01 (14)
C2—N3—C1102.81 (10)C5—C4—H4120.5
C2—N4—H4A116.4 (10)C3—C4—H4120.5
C2—N4—H4B112.7 (10)C6—C5—C4119.12 (14)
H4A—N4—H4B117.2 (14)C6—C5—H5120.4
C7—N5—C3117.65 (12)C4—C5—H5120.4
N1—C1—N3115.02 (12)C5—C6—C7118.36 (14)
N1—C1—C3122.04 (12)C5—C6—H6120.8
N3—C1—C3122.94 (11)C7—C6—H6120.8
N3—C2—N2110.03 (12)N5—C7—C6123.76 (15)
N3—C2—N4127.19 (11)N5—C7—H7118.1
N2—C2—N4122.71 (12)C6—C7—H7118.1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N2—H2N···N5i0.90 (2)2.01 (2)2.9010 (16)171 (1)
N4—H4A···N3ii0.90 (2)2.11 (2)2.9971 (16)172 (1)
N4—H4B···N1i0.93 (2)2.19 (2)3.0264 (16)151 (1)
Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) −x+1, −y, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N2—H2N···N5i0.90 (2)2.01 (2)2.9010 (16)171 (1)
N4—H4A···N3ii0.90 (2)2.11 (2)2.9971 (16)172 (1)
N4—H4B···N1i0.93 (2)2.19 (2)3.0264 (16)151 (1)
Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) −x+1, −y, −z+1.
Acknowledgements top

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

references
References top

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