3,6-Di-4-pyridyl-1,4-dihydro-1,2,4,5-tetra­zine

The mol­ecule of the title compound, C₁₂H₁₀N₆, which is V-shaped due to the boat conformation of the dihydro­tetra­zine ring, has crystallographic C₂ symmetry. The dihedral angle between the planes of the two pyridine rings is 31.57 (3)°. Mol­ecules are linked by weak N—H...N and C—H...N hydrogen bonds, forming a two-dimensional polymeric structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.051
• wR factor = 0.128
• Data-to-parameter ratio = 12.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.32
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Tetrazine derivatives have been widely used in pesticides and herbicides as they have a high potential for biological activity and possess a wide range of antiviral and antitumor properties (Sauer, 1996). Herein, we report the crystal structure of a new tetrazine derivative, 3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine.

The molecule of the title compound, which has a crystallographic C₂ symmetry is shown in Fig. 1. The title compound can be regarded as a V-shaped tetrazine with the dihedral angle between the pyridine rings of 31.57 (3) °. In the crystalline state, each molecule is connected to four adjacent molecules to form a two-dimensional (4,4) hydrogen-bonding network by the intermolecular N—H···N and weak C—H···N hydrogen bonds (Fig. 2.). Crystal structures of several other tetrazine derivatives with a similar shape have been reported (Bradford et al., 2004; Caira et al., 1976; Liou et al., 1996; Zachara et al., 2004; Rao & Hu, 2005).

Related literature

For related structures, see: Bradford et al. (2004); Caira et al. (1976); Liou et al. (1996); Zachara et al. (2004); Rao & Hu (2005). For ralated literature on tetrazines, see: Sauer (1996).

S2. Experimental

A mixture of 4-cyanopyridine (0.416g, 4.0 mmol), 80% hydrazine hydrate (5 ml), CoCl₂.6H₂O (0.238g, 1.0 mmol) and 95% ethanol (4 ml) was heated in a 15-mL Teflon-lined autoclave at 120°C deg for 3 days, followed by slow cooling (5°/h deg) to room temperature. The resulting mixture was washed with 95% ethanol, and red block crystals were collected and dried in air [yield 3.0% (14.3 mg) based on 4-cyanopyridine].

S3. Refinement

H atoms bonded to N atoms were located in an electron-density difference map and refined isotropically without any restraints. Other H atoms were positioned geometrically and refined using a riding model with C—H = 0.93 Å and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART (Bruker, 2000); data reduction: SAINT (Bruker, 2000); 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

	Fig. 1. The molecular structure of the title compound with 30% displacement ellipsoids. Symmetry code for the atoms designated with A: -1/2 - x, 1/2 - y, z.
	Fig. 2. A two-dimensional (4,4) hydrogen-bond network of the title compound viewed along the c axis

3,6-Di-4-pyridyl-1,4-dihydro-1,2,4,5-tetrazine

Crystal data

C12H10N6	F(000) = 496
Mr = 238.26	Dx = 1.406 Mg m^−3
Orthorhombic, Pccn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2ac	Cell parameters from 820 reflections
a = 11.2862 (18) Å	θ = 2.5–28.0°
b = 14.481 (2) Å	µ = 0.09 mm^−1
c = 6.8864 (12) Å	T = 293 K
V = 1125.4 (3) Å^3	Block, red
Z = 4	0.50 × 0.10 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1105 independent reflections
Radiation source: fine-focus sealed tube	938 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
Detector resolution: 0 pixels mm^-1	θmax = 26.0°, θmin = 2.8°
ϕ and ω scans	h = −13→10
Absorption correction: multi-scan (SADABS; Bruker, 2000)	k = −17→17
Tmin = 0.955, Tmax = 0.991	l = −3→8
4214 measured reflections

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.128	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0618P)^2 + 0.3052P] where P = (Fo^2 + 2Fc^2)/3
1105 reflections	(Δ/σ)max < 0.001
86 parameters	Δρmax = 0.20 e Å^−3
0 restraints	Δρmin = −0.14 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
C1	0.56160 (17)	0.17370 (13)	0.1811 (4)	0.0589 (7)
H1A	0.5769	0.2351	0.1500	0.071*
C2	0.65246 (19)	0.11530 (16)	0.2327 (4)	0.0683 (8)
H2A	0.7286	0.1397	0.2370	0.082*
C3	0.52968 (17)	−0.00510 (13)	0.2686 (3)	0.0463 (5)
H3A	0.5172	−0.0671	0.2971	0.056*
C4	0.43215 (16)	0.04780 (12)	0.2202 (3)	0.0390 (5)
H4A	0.3571	0.0214	0.2176	0.047*
C5	0.44678 (15)	0.13961 (11)	0.1762 (3)	0.0322 (4)
C6	0.34693 (13)	0.20078 (11)	0.1238 (2)	0.0296 (4)
N1	0.63928 (15)	0.02634 (11)	0.2770 (3)	0.0526 (5)
N2	0.36287 (11)	0.28776 (9)	0.1283 (2)	0.0331 (4)
N3	0.26087 (12)	0.33789 (10)	0.0671 (2)	0.0332 (4)
H3B	0.2708 (17)	0.3931 (14)	0.097 (3)	0.047 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0310 (11)	0.0379 (11)	0.108 (2)	−0.0006 (8)	−0.0039 (11)	0.0119 (11)
C2	0.0282 (11)	0.0536 (13)	0.123 (2)	0.0004 (9)	−0.0073 (12)	0.0094 (14)
C3	0.0396 (13)	0.0355 (10)	0.0639 (14)	0.0077 (8)	−0.0012 (9)	0.0042 (9)
C4	0.0294 (10)	0.0324 (9)	0.0553 (12)	0.0011 (7)	−0.0008 (8)	0.0023 (8)
C5	0.0273 (9)	0.0314 (9)	0.0379 (9)	0.0025 (7)	0.0029 (7)	−0.0026 (7)
C6	0.0255 (9)	0.0272 (8)	0.0360 (9)	−0.0013 (6)	0.0027 (7)	−0.0009 (7)
N1	0.0357 (10)	0.0463 (10)	0.0756 (13)	0.0111 (7)	−0.0021 (8)	0.0028 (9)
N2	0.0238 (8)	0.0283 (7)	0.0471 (9)	0.0007 (6)	0.0036 (6)	0.0006 (6)
N3	0.0270 (8)	0.0239 (7)	0.0487 (9)	0.0011 (6)	0.0019 (6)	0.0030 (6)

Geometric parameters (Å, º)

C1—C2	1.376 (3)	C4—C5	1.374 (2)
C1—C5	1.387 (2)	C4—H4A	0.9300
C1—H1A	0.9300	C5—C6	1.478 (2)
C2—N1	1.332 (3)	C6—N2	1.273 (2)
C2—H2A	0.9300	C6—N3^i	1.395 (2)
C3—N1	1.319 (2)	N2—N3	1.4249 (18)
C3—C4	1.382 (3)	N3—C6^i	1.395 (2)
C3—H3A	0.9300	N3—H3B	0.83 (2)
C2—C1—C5	118.94 (18)	C4—C5—C1	116.82 (16)
C2—C1—H1A	120.5	C4—C5—C6	122.84 (15)
C5—C1—H1A	120.5	C1—C5—C6	120.33 (16)
N1—C2—C1	124.8 (2)	N2—C6—N3^i	121.83 (14)
N1—C2—H2A	117.6	N2—C6—C5	118.64 (15)
C1—C2—H2A	117.6	N3^i—C6—C5	119.51 (14)
N1—C3—C4	124.48 (18)	C3—N1—C2	115.36 (17)
N1—C3—H3A	117.8	C6—N2—N3	112.51 (13)
C4—C3—H3A	117.8	C6^i—N3—N2	114.66 (12)
C5—C4—C3	119.61 (17)	C6^i—N3—H3B	115.7 (14)
C5—C4—H4A	120.2	N2—N3—H3B	107.9 (14)
C3—C4—H4A	120.2

Symmetry code: (i) −x+1/2, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3B···N1^ii	0.83 (2)	2.35 (2)	3.142 (2)	159.8 (18)
C3—H3A···N2^iii	0.93	2.55	3.312 (2)	139
C4—H4A···N1^iv	0.93	2.55	3.475 (3)	171

Symmetry codes: (ii) −x+1, y+1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) x−1/2, −y, −z+1/2.