5-Amino-3-(4H-1,2,4-triazol-4-yl)-1H-1,2,4-triazole

Bing Liu; João P C Tomé; Luís Cunha-Silva; Filipe A Almeida Paz

doi:10.1107/S1600536812034691

. 2012 Aug 11;68(Pt 9):o2700–o2701. doi: 10.1107/S1600536812034691

5-Amino-3-(4H-1,2,4-triazol-4-yl)-1H-1,2,4-triazole

Bing Liu ^a,^b, João P C Tomé ^c, Luís Cunha-Silva ^b, Filipe A Almeida Paz ^a,^*

PMCID: PMC3435720 PMID: 22969591

Abstract

The asymmetric unit of the title compound, C₄H₅N₇, comprises two independent but virtually superimposable molecules. Each molecule is planar with the dihedral angles between the five-membered rings being 2.8 (3) and 2.1 (3)°. The crystal structure is formed by an extensive network of relatively strong N—H⋯N hydrogen-bond interactions. Individual molecules are arranged into supramolecular zigzag chains running parallel to [001] by way of the strongest N—H⋯N interactions. Adjacent chains are interconnected by rather long (D⋯A distances range from ca 3.00 to 3.03 Å) but highly directional (interaction angles above ca 173°) hydrogen bonds forming a supramolecular layer in the bc plane.

Related literature

For the synthesis of 1-butyl-3-methylimidazolium bromide and 1,2-diformylhydrazine, see: Liu et al. (2007 ▶); Parnham & Morris (2006 ▶). For the use of triazole molecules, see: Wang et al. (2012 ▶); Zhang et al. (2009 ▶). For previous research studies on crystal engineering approaches, see: Fernandes et al. (2011 ▶); Silva et al. (2011 ▶); Amarante et al. (2009 ▶); Paz & Klinowski (2007 ▶). For graph-set notation, see: Grell et al. (1999 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₄H₅N₇
M _r = 151.15
Monoclinic,
a = 13.765 (3) Å
b = 5.9378 (12) Å
c = 16.635 (4) Å
β = 112.914 (12)°
V = 1252.4 (5) Å³
Z = 8
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 293 K
0.10 × 0.05 × 0.03 mm

Data collection

Bruker X8 Kappa CCD APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1998 ▶) T _min = 0.988, T _max = 0.996
8003 measured reflections
2192 independent reflections
975 reflections with I > 2σ(I)
R _int = 0.079

Refinement

R[F ² > 2σ(F ²)] = 0.073
wR(F ²) = 0.226
S = 0.96
2192 reflections
217 parameters
8 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.52 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT-Plus (Bruker, 2005 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2009 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812034691/tk5136sup1.cif

e-68-o2700-sup1.cif^{(17.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812034691/tk5136Isup2.hkl

e-68-o2700-Isup2.hkl^{(107.8KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812034691/tk5136Isup3.cdx

Supplementary material file. DOI: 10.1107/S1600536812034691/tk5136Isup4.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—H1A⋯N14ⁱ	0.90 (1)	2.43 (2)	3.239 (6)	150 (4)
N1—H1B⋯N4ⁱⁱ	0.90 (1)	2.11 (1)	3.002 (6)	173 (5)
N2—H2⋯N13ⁱ	0.90 (1)	1.93 (2)	2.772 (6)	155 (5)
N8—H8A⋯N7	0.90 (1)	2.43 (2)	3.264 (6)	154 (4)
N8—H8B⋯N11ⁱⁱⁱ	0.90 (1)	2.14 (1)	3.034 (6)	176 (5)
N10—H10⋯N6	0.90 (1)	1.91 (2)	2.777 (6)	161 (5)

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

Acknowledgments

The authors gratefully acknowledge the Fundação para a Ciência e a Tecnologia (FCT, MEC, Portugal), the European Union, QREN, FEDER, COMPETE for financial support by the strategic projects PEst-C/CTM/LA0011/2011 (to CICECO) and Pest-C/EQB/LA0006/2011 (to REQUIMTE), the R&D projects PTDC/CTM/100357/2008 and PTDC/QUI-QUI/098098/2008 (FCOMP-01–0124-FEDER-010785), as well as the post-doctoral research grant SFRH/BPD/47566/2008 (to BL). They also wish to thank FCT for the specific funding towards the purchase of the single-crystal X-ray diffractometer.

supplementary crystallographic information

Comment

In the context of our interest in Crystal Engineering approaches (Wang et al. 2012; Fernandes et al.; 2011; Silva et al., 2011; Amarante, Gonçalves et al., 2009; Amarante et al., 2009; Paz & Klinowski, 2007), we are currently designing new triazole molecules which could be simultaneously employed in the construction of novel Metal-Organic Frameworks (MOFs) or organic crystals. We note that this type of molecule has received considerable interest in the synthesis of polynuclear complexes and in the preparation of MOFs (Zhang et al., 2009). A survey in the Cambridge structural Database (Allen, 2002) and in the literature revealed that the use of the asymmetrical bridging bitriazole molecule 5-amino-3-(1,2,4-triazol-4-yl)-1H-1,2,4-triazole (HAtrtr) has not been reported to date, either in MOFs nor in organic crystals. Furthermore, to the best of our knowledge, its crystal structure has not been reported. Following our recent efforts we were able to isolate good-quality single-crystals of the title compound as a minor secondary phase and here we wish to report its crystal structure at ambient temperature.

The asymmetric unit of the title compound (I) comprises two whole molecules (i.e., Z'=2) of HAtrtr as depicted in Fig. 1. We note that these two individual moieties are almost perfectly overlaid by assuming a combination of both inversion and molecular flexibility (maximum distance of ca 0.021 Å with RMS of ca 0.014 Å). Nevertheless, this feature is not described by crystal symmetry as the "head-to-tail" orientation of the molecules can not be described by the screw-axis parallel to the b-axis of the unit cell. Both molecules are almost planar with the dihedral angles between the 1,2,4-triazole rings being only of ca 2.8 and 2.1°. In addition, the medium planes of all non-hydrogen atoms of each molecule subtend an angle of just ca 7.1°, indicating that the molecules can also be envisaged as coplanar.

HAtrtr is rich in groups capable of forming strong N—H···N hydrogen bonding interactions (see Table 1 for further geometrical details), which direct the crystal packing features of the title compound. The most striking intermolecular interactions concern the double donation of hydrogen atoms from each 5-amino-3-(1,2,4-triazole moiety to the 1,2,4-triazole group of an adjacent molecule (N1—H1A···N14, N2—H2···N13, N8—H8A···N7 and N10—H10···N6), forming a R₂²(7) graph set motif (dashed yellow lines in Fig. 2) (Grell et al., 1999). This supramolecular motif constitutes the basis of the formation of a supramolecular zigzag tape parallel to the c axis, for which the repeating motif are the two molecules composing the asymmetric unit. Tapes are interconnected by additional N—H···N interactions (N1—H1B···N4 and N8—H8B···N11) which, despite being slightly long (d_D···A ranging from 3.002 (6) to 3.034 (6) Å), are nevertheless highly directional with the interaction angles approaching linearity (of ca 173 and 176°). Noteworthy, these inter-chain connections are further strengthened by the presence of two weak C—H···N interactions (not represented): C3—H3···N3ⁱ with d_C···N=3.389 (6) Å and <(CHN)=174°; C8—H8···N9ⁱⁱ with d_C···N=3.435 (6) Å and <(CHN)=167° (symmetry codes: (i) x, 1 + y, z; (ii) x, -1 + y, z). The combination of these N—H···N and C—H···N contacts can be described by the R₂²(8) graph set motif.

The hydrogen bonding interactions connecting adjacent molecular units and summarized in the previous paragraph lead to the formation of a two-dimensional supramolecular layer placed in the bc plane as shown in Fig. 2. Individual layers close pack parallel to the a-axis of the unit cell mediated by offset π-π contacts between HAtrtr molecules (Fig. 3 and Table 2 for intercentroid distances). Noteworthy, the inter-layer distance along the a axis alternates: layers are disposed into pairs so to promote the aforementioned strong offset π-π contacts within one pair; connections between adjacent pairs of supramolecular layers are weaker (i.e. longer inter-centroid distances - not shown).

Experimental

3,5-Di(amino)-1,2,4-triazole (98% purity) and Mn(OAc)₂^.4H₂O (99%+ purity) were purchased from Sigma-Aldrich and were used as received without further purification. 5-Amino-3-(1,2,4-triazol-4-yl)-1H-1,2,4-triazole and 1,2-diformylhydrazine were prepared by methods reported in the literature (Liu et al., 2007). 1-Butyl-3-methylimidazolium bromide ([BMI]Br) was also prepared according to literature procedures (Parnham & Morris, 2006) (pale-yellow oil; yield: 78°).

1,2-Diformylhydrazine (0.1 mol; 8.8095 g) and 3,5-di(amino)-1,2,4-triazole (0.05 mol; 4.9564 g) were mixed in a 25 mL Teflon-lined stainless-steel reaction vessel and heated at 170 °C for 3 days in a furnace. After this time, the vessel was allowed to cool slowly to ambient temperature yielding 5-amino-3-(1,2,4-triazol-4-yl)-1H-1,2,4-triazole (HAtrtr) as a white microcrystalline powder. The solid was then washed with copious amounts of water and ethanol and dried at ca 60 °C for 24 h. Yield: 6.85 g, 67.4%.

HAtrtr (0.2 mmol, 0.0407 g) and Mn(OAc)₂^.4H₂O (1.0 mmol, 0.2451 g) were mixed with ca 0.50 g of [BMI]Br in a 25 mL teflon-lined stainless-steel reaction vessel. The resulting mixture was heated to 110 °C for 7 days. The vessel was then allowed to cool to ambient temperature at a rate of ca 1 °C/h. Small colourless platelets of HAtrtr were formed as a minor secondary product, whose crystal structure is reported in this manuscript.