A new polymorph of 5,5′-(ethane-1,2-di­yl)bis­­(1H-tetra­zole)

The asymmetric unit of the title compound, C₄H₆N₈, contains a quarter of the mol­ecule, which possesses a crystallographically imposed centre of symmetry with all non-H atoms situated on a mirror plane. The crystal packing exhibits inter­molecular N—H⋯N hydrogen bonds and π–π stacking inter­actions between the tetra­zole rings of adjacent mol­ecules [centroid–centroid distance = 3.4402 (10) Å].

Related literature

For the previously reported polymorph, see: Shen et al. (2011). For the synthesis of the title compound and for related structures, see: Chafin et al. (2008); Diop et al. (2002). For the application of tetra­zole derivatives in coordination chemistry and energetic materials, see: Zhao et al. (2008); Singh et al. (2006).

Experimental

Crystal data

• C₄H₆N₈

• M_r = 166.17

• Monoclinic, C 2/m

• a = 10.951 (3) Å

• b = 6.678 (2) Å

• c = 5.0329 (14) Å

• β = 114.250 (4)°

• V = 335.58 (17) ų

• Z = 2

• Mo Kα radiation

• μ = 0.12 mm⁻¹

• T = 296 K

• 0.31 × 0.27 × 0.13 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2008) T_min = 0.962, T_max = 0.985

• 819 measured reflections

• 320 independent reflections

• 293 reflections with I > 2σ(I)

• R_int = 0.022

Refinement

• R[F² > 2σ(F²)] = 0.037

• wR(F²) = 0.098

• S = 1.09

• 320 reflections

• 37 parameters

• H-atom parameters constrained

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.26 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4⋯N2^i	0.86	2.10	2.943 (3)	166
Symmetry code: (i) x, y, z+1.

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

Due to the rich coordination modes and high content of nitrogen, tetrazole compounds have been studied for more than one hundred years and widely applied in coordination chemistry (Zhao et al., 2008) and energetic materials (Singh et al., 2006). As an important derivative of tetrazole, 5,5'-ethane-1,2-diylbis(1H-tetrazole) has been utilized to construct functional and interesting coordination compounds owing to its flexible coordination modes. The crystal structure of the title compound has been previously reported by Shen et al. (2011) in the monoclinic space group P2₁/c (Z = 4). We report here the synthesis and crystal structure of a new polymorph of the title compound, (I).

Polymorph I crystallizes in the space group C2/m (Z = 2) with one-fourth part of the molecule in the asymmetric unit. In the crystal, all non-H atoms are situated on the mirror plane. Similar to the previously reported polymorph, each pair tetrazolate rings in I are coplanar linked by flexible —CH₂—CH₂— group (Fig. 1). The bond lengths and angles in I are within normal ranges and comparable with the previously reported structure. N—H···N hydrogen bonds (Table 1) link the adjacent molecules into one-dimensional belts along the c axis, whereas molecules of the previously reported polymorph are connected into a three dimensional supramolecular framework. The N···N distance [2.943 (3) Å] is longer than that seen in the previously published polymorph [2.840 (2) and 2.873 (2) Å] (Shen et al., 2011). π-π stacking interactions between tetrazole rings of adjacent molecules [centroid-centroid distances = 3.4402 (10) Å] further consolidate the crystal packing.

Related literature

For the previously reported polymorph, see: Shen et al. (2011). For the synthesis of the title compoundnd and for related structures, see: Chafin et al. (2008); Diop et al. (2002). For the application of tetrazole derivatives in coordination chemistry and energetic materials, see: Zhao et al. (2008); Singh et al. (2006).

S2. Experimental

The title compound was prepared from a mixture of sodium azide and succinonitrile using the method described by Chafin et al. (2008). Colourless block single crystals were obtained by recrystallization of the title compound from ethanol.

S3. Refinement

All H atoms were positioned geometrically (C—H = 0.97 Å and N—H = 0.86 Å) and refined as riding with U_iso(H) = 1.2U_eq(C,N).

Computing details

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. The molecular structure of I showing the atomic numbering and 30% probability displacement ellipsoids [symmetry code: (A) -x, y, -z].

5,5'-(Ethane-1,2-diyl)bis(1H-tetrazole)

Crystal data

C4H6N8	F(000) = 172
Mr = 166.17	Dx = 1.644 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 501 reflections
a = 10.951 (3) Å	θ = 3.7–25.9°
b = 6.678 (2) Å	µ = 0.12 mm^−1
c = 5.0329 (14) Å	T = 296 K
β = 114.250 (4)°	Block, colorless
V = 335.58 (17) Å^3	0.31 × 0.27 × 0.13 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer	320 independent reflections
Radiation source: fine-focus sealed tube	293 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
φ and ω scans	θmax = 24.9°, θmin = 3.7°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −7→12
Tmin = 0.962, Tmax = 0.985	k = −7→7
819 measured reflections	l = −5→5

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.098	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.059P)^2 + 0.15P] where P = (Fo^2 + 2Fc^2)/3
320 reflections	(Δ/σ)max < 0.001
37 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.26 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
N1	0.19695 (18)	0.0000	−0.1482 (4)	0.0402 (6)
N2	0.3293 (2)	0.0000	−0.0872 (4)	0.0407 (6)
N3	0.4005 (2)	0.0000	0.1919 (4)	0.0393 (6)
N4	0.31215 (19)	0.0000	0.3136 (4)	0.0355 (6)
H4	0.3323	0.0000	0.4977	0.043*
C1	0.1877 (2)	0.0000	0.1035 (5)	0.0327 (6)
C2	0.0608 (2)	0.0000	0.1451 (5)	0.0378 (6)
H2A	0.0582	0.1175	0.2559	0.045*	0.50
H2B	0.0582	−0.1175	0.2559	0.045*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0237 (11)	0.0681 (14)	0.0269 (12)	0.000	0.0087 (9)	0.000
N2	0.0244 (11)	0.0676 (14)	0.0314 (12)	0.000	0.0129 (9)	0.000
N3	0.0238 (10)	0.0650 (13)	0.0305 (11)	0.000	0.0127 (8)	0.000
N4	0.0230 (10)	0.0589 (12)	0.0233 (10)	0.000	0.0082 (8)	0.000
C1	0.0227 (12)	0.0475 (13)	0.0256 (11)	0.000	0.0076 (9)	0.000
C2	0.0200 (13)	0.0643 (15)	0.0278 (13)	0.000	0.0085 (10)	0.000

Geometric parameters (Å, º)

N1—C1	1.312 (3)	N4—H4	0.8600
N1—N2	1.353 (3)	C1—C2	1.488 (3)
N2—N3	1.297 (3)	C2—C2^i	1.519 (4)
N3—N4	1.341 (3)	C2—H2A	0.9700
N4—C1	1.338 (3)	C2—H2B	0.9700
C1—N1—N2	106.33 (19)	N4—C1—C2	126.6 (2)
N3—N2—N1	110.93 (18)	C1—C2—C2^i	111.4 (2)
N2—N3—N4	105.61 (18)	C1—C2—H2A	109.3
C1—N4—N3	109.32 (18)	C2^i—C2—H2A	109.3
C1—N4—H4	125.3	C1—C2—H2B	109.3
N3—N4—H4	125.3	C2^i—C2—H2B	109.3
N1—C1—N4	107.8 (2)	H2A—C2—H2B	108.0
N1—C1—C2	125.6 (2)
C1—N1—N2—N3	0.0	N3—N4—C1—N1	0.0
N1—N2—N3—N4	0.0	N3—N4—C1—C2	180.0
N2—N3—N4—C1	0.0	N1—C1—C2—C2^i	0.0
N2—N1—C1—N4	0.0	N4—C1—C2—C2^i	180.0
N2—N1—C1—C2	180.0

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4···N2^ii	0.86	2.10	2.943 (3)	166

Symmetry code: (ii) x, y, z+1.