6-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetra­zin-3(2H)-one

Suponitsky, K.Y.; Chernyshev, V.M.; Mazharova, A.G.; Palysaeva, N.V.; Sheremetev, A.B.

doi:10.1107/S1600536813027360

organic compounds

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ISSN: 2056-9890

Volume 69| Part 11| November 2013| Pages o1630-o1631

doi:10.1107/S1600536813027360

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6-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazin-3(2H)-one

Kyrill Yu. Suponitsky,^a ^* Victor M. Chernyshev,^b Anna G. Mazharova,^b Nadezhda V. Palysaeva ^c and Aleksei B. Sheremetev ^c

^aA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilova St, 119991 Moscow, Russian Federation, ^bSouth-Russia State Technical University, 346428 Novocherkassk, Russian Federation, and ^cN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prosp, 119991 Moscow, Russian Federation
^*Correspondence e-mail: kirshik@yahoo.com

(Received 1 October 2013; accepted 4 October 2013; online 12 October 2013)

The title compound, C₇H₈N₆O, represents the keto form and adopts a nearly planar structure (r.m.s. deviation of the non-H atoms = 0.072 Å). In the crystal, molecules form spiral chains along the c axis by N—H⋯N hydrogen bonds. The chains are linked to each other by weak C—H⋯O hydrogen bonds, forming a three-dimensional framework.

CCDC reference: 964975

Related literature

For review on nucleophilic displacement at the 1,2,4,5-tetrazine ring, see: Clavier & Audebert (2010 ); Tolshchina et al. (2013 ). For the synthesis of 3-hydroxy-1,2,4,5-tetrazines, see: Ishmetova et al. (2009 ); Sheremetev et al. (2012a ,b ). For the structure of 3-hydroxy-1,2,4,5-tetrazine, see: Yeh et al. (1994 ). For a review on oxo-hydroxy tautomerism of various azines, see: Stanovnik et al. (2006 ). For standard bond lengths, see: Allen et al. (1987 ).

Experimental

Crystal data

C₇H₈N₆O
M_r = 192.19
Orthorhombic, P n a 2₁
a = 12.1431 (11) Å
b = 12.6551 (12) Å
c = 5.3907 (5) Å
V = 828.40 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 120 K
0.28 × 0.22 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
14157 measured reflections
1353 independent reflections
1228 reflections with I > 2σ(I)
R_int = 0.050

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.094
S = 1.05
1353 reflections
133 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4⋯N1ⁱ	0.89 (3)	2.00 (3)	2.863 (2)	161 (3)
C2—H2A⋯O1ⁱⁱ	0.95	2.40	3.193 (3)	141
Symmetry codes: (i) $[-x+2, -y+1, z+{\script{1\over 2}}]$ ; (ii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z-{\script{3\over 2}}]$ .

Data collection: APEX (Bruker, 2009 ); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PLATON (Spek, 2009 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 964975

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536813027360/kq2010sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813027360/kq2010Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813027360/kq2010Isup3.cml

checkCIF report

Comment top

Over the last decade, broad studies of nucleophilic displacemet at 1,2,4,5-tetrazine ring have demonstrated that the highly electron-withdrawing aromatic ring exhibit a rich diversity of chemical behavior, and today 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine 1 has become common precursor to various tetrazine derivatives (Clavier & Audebert, 2010; Tolshchina et al., 2013). The displacement of the dimethylpyrazolyl moiety in compound 1 by a wider range of N-nucleophiles has been well documented (Sheremetev et al., 2012a, 2012b), while reactions of the tetrazine 1 with O-nucleophiles have been studied to a lesser extent (Yeh et al., 1994; Ishmetova et al., 2009). Here, we wish to report the unexpected discovery of an unusual dimethylpyrazolyl moiety displacement of compound 1 when it is treated with N-nucleophile, such as 3-amino-1-tret-butyl-1,2,4-triazole 2.

Upon a refluxing of compound 1 with amine 2 and K₂CO₃ in acetonitrile and following treatment with water, an step required to workup of the reaction mixture, it was found that instead of introduction of N-nucleophile (with a formation of compound 3) the reaction gave the hydroxy derivative 4' (Figure 1).

According to X-ray data, the title compound adopts nearly planar structure (r.m.s. deviation of the non-hydrogen atoms is 0.072 Å) (Figure 2). In general, it can exist in two tautomeric forms (Stanovnik et al., 2006) as shown in Figure 1. The hydrogen atom H4 was localized and refined at the N4 nitrogen atom that means that the title compound exists in keto-form, and the equilibrium favors the tautomer 4'. This is also supproted by the bond length distribution in the tetrazin-3-one: the C7—O1 (1.215 (3) Å) bond corresponds to normal carbonyl bond (standard X-ray C═O value is in the range of 1.192–1.235 Å (Allen et al. 1987), while the N3—C6 (1.300 (2) Å) and N5—N6 (1.286 (2) Å) bonds are significantly shorter than the C7—N4 (1.368 (3) Å), N3—N4 (1.384 (2) Å), C6—N5 (1.377 (2) Å) and N6—C7 (1.427 (2) Å) bonds.

The crystal structure of 4' is stabilized by intermolecular N—H···N and C—H···O hydrogen bonds (Table 1). By means of the N4—H4···N1ⁱ hydrogen bond, molecules are connected into spiral chains along the c axis (Figure 3). Those chains are linked into 3D-framework (Figure 3) by the C2—H2A···O1ⁱⁱ contacts. Symmetry codes: (i) –x+2, –y+1, z+1/2; (ii) –x+3/2, y–1/2, z–3/2.

Related literature top

For review on nucleophilic displacement at the 1,2,4,5-tetrazine ring, see: Clavier & Audebert (2010); Tolshchina et al. (2013). For the synthesis of 3-hydroxy-1,2,4,5-tetrazines, see: Ishmetova et al. (2009); Sheremetev et al. (2012a,b). For the structure of 3-hydroxy-1,2,4,5-tetrazine, see: Yeh et al. (1994). For a review on oxo-hydroxy tautomerism of various azines, see: Stanovnik et al. (2006). For standard bond lengths, see: Allen et al. (1987).

Experimental top

The X-ray quality crystals of the title compound were grown by slow evaporation of acetonitrile solution.

All the reagents were of analytical grade, purchased from commercial sources, and used as received. Infrared spectra were determined in KBr pellets on a Perkin-Elmer Model 577 spectrometer. Mass-spectra were recorded on a Varian MAT-311 A instrument. The ¹H, ¹³C and ¹⁵N NMR spectra (external standard: CH₃NO₂) were recorded at 300.13, 75.47 and 50.7 MHz, respectively. The chemical shift values (δ, p.p.m.) are expressed relative to the chemical shift of the solvent-d or to external standard without correction nitromethane (¹⁴N and ¹⁵N). Melting points were determined on Gallenkamp melting point apparatus and are uncorrected.

6-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazin-3(2H)-one (4'). A mixture of 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine 1 (0.27 g, 1 mmol), 3-amino-1-tretbutyl-1,2,4-triazole 2 (0.14 g, 1 mmol), and K₂CO₃ (0.14 g, 1 mmol) was refluxed in dry acetonitrile (10 mL) for 3 d. The reaction mixture was then cooled and a violet solid formed was collected by filtration. The solid was dissolved in water (10 mL), acidifed with 3% HCl to pH 1 and cooled to 278 K. A solid was collected by filtration, washed with 1% HCl and hexane and crystallized from MeCN/H₂O, yield 0.15 g (82%), mp 483–484 K (dec.); IR (KBr, cm^-1): ν = 3135–2823, 1744, 1706, 1693, 1553, 1506, 1435, 1405, 1373, 1263, 1161, 1138, 1105, 1063, 1025, 993, 975, 836, 808. ¹H MNR (DMSO-d₃, 293 K): δ = 2.20 and 2.38 (3H+3H, C1—CH₃ and C3—CH₃), 6.17 (c, 1H, CH), 8.51 (br, 1H, OH); ¹³C MNR (DMSO-d₃, 293 K): δ = 13.3, 13.2, 108.9, 141.9, 147.7, 150.7, 152.0. ¹⁵N MNR (DMSO-d₃, 293 K): δ = –1.87, –35.0, –77.6, –173.3. Anal. Calcd. for C₇H₈N₆O (192.17): C, 43.75; H, 4.20; N, 43.73. Found: C, 43.81; H, 4.24; N, 43.61.

Computing details top

Data collection: APEX (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Figures top

	Fig. 1. Synthesis of the title compound.
	Fig. 2. General view of the structure of the title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.
	Fig. 3. Crystal packing fragment of the title compound. Hydrogen atoms of the methyl groups are omitted for clarity. Dashed lines indicate the intermolecular N—H···N and C—H···O hydrogen bonds.

6-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazin-3(2H)-one top

Crystal data top

C₇H₈N₆O	D_x = 1.541 Mg m⁻³
M_r = 192.19	Melting point = 474–473 K
Orthorhombic, Pna2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 4489 reflections
a = 12.1431 (11) Å	θ = 2.3–30.2°
b = 12.6551 (12) Å	µ = 0.11 mm⁻¹
c = 5.3907 (5) Å	T = 120 K
V = 828.40 (13) Å³	Prizm, red
Z = 4	0.28 × 0.22 × 0.20 mm
F(000) = 400

Data collection top

Bruker APEXII CCD diffractometer	1228 reflections with I > 2σ(I)
Radiation source: sealed tube	R_int = 0.050
Graphite monochromator	θ_max = 30.2°, θ_min = 2.3°
ϕ and ω scans	h = −17→17
14157 measured reflections	k = −17→17
1353 independent reflections	l = −7→7

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.037	Hydrogen site location: mixed
wR(F²) = 0.094	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.0529P)² + 0.2463P] where P = (F_o² + 2F_c²)/3
1353 reflections	(Δ/σ)_max < 0.001
133 parameters	Δρ_max = 0.40 e Å⁻³
1 restraint	Δρ_min = −0.28 e Å⁻³

Crystal data top

C₇H₈N₆O	V = 828.40 (13) Å³
M_r = 192.19	Z = 4
Orthorhombic, Pna2₁	Mo Kα radiation
a = 12.1431 (11) Å	µ = 0.11 mm⁻¹
b = 12.6551 (12) Å	T = 120 K
c = 5.3907 (5) Å	0.28 × 0.22 × 0.20 mm

Data collection top

Bruker APEXII CCD diffractometer	1228 reflections with I > 2σ(I)
14157 measured reflections	R_int = 0.050
1353 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	1 restraint
wR(F²) = 0.094	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.40 e Å⁻³
1353 reflections	Δρ_min = −0.28 e Å⁻³
133 parameters

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

	x	y	z	U_iso*/U_eq
O1	0.86033 (12)	0.65658 (12)	1.3631 (3)	0.0238 (3)
N1	0.85424 (13)	0.38253 (13)	0.4472 (3)	0.0155 (3)
N2	0.76721 (12)	0.41809 (12)	0.5895 (3)	0.0144 (3)
N3	0.89653 (13)	0.50888 (12)	0.8195 (3)	0.0158 (3)
N4	0.91664 (13)	0.57202 (12)	1.0123 (3)	0.0155 (3)
H4	0.989 (2)	0.583 (2)	1.029 (7)	0.034 (7)*
N5	0.70626 (13)	0.52560 (13)	0.9220 (3)	0.0188 (4)
N6	0.72745 (13)	0.58417 (14)	1.1110 (4)	0.0202 (4)
C1	0.80934 (15)	0.31818 (14)	0.2799 (4)	0.0148 (3)
C2	0.69351 (15)	0.31263 (15)	0.3124 (4)	0.0173 (4)
H2A	0.6432	0.2729	0.2149	0.021*
C3	0.66818 (15)	0.37567 (14)	0.5118 (4)	0.0156 (4)
C4	0.87981 (15)	0.26232 (15)	0.0946 (4)	0.0186 (4)
H4A	0.9493	0.3008	0.0741	0.028*
H4B	0.8413	0.2591	−0.0650	0.028*
H4C	0.8951	0.1905	0.1529	0.028*
C5	0.55864 (15)	0.39560 (17)	0.6288 (4)	0.0227 (4)
H5A	0.5624	0.3785	0.8059	0.034*
H5B	0.5028	0.3512	0.5489	0.034*
H5C	0.5389	0.4702	0.6085	0.034*
C6	0.79310 (14)	0.48639 (14)	0.7861 (4)	0.0139 (3)
C7	0.83879 (16)	0.60685 (15)	1.1765 (4)	0.0168 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0219 (7)	0.0287 (7)	0.0207 (7)	0.0014 (6)	−0.0019 (6)	−0.0093 (6)
N1	0.0105 (6)	0.0199 (7)	0.0162 (7)	−0.0001 (6)	0.0027 (6)	−0.0025 (6)
N2	0.0093 (6)	0.0197 (7)	0.0144 (7)	−0.0004 (5)	0.0012 (6)	−0.0029 (6)
N3	0.0123 (7)	0.0206 (7)	0.0145 (8)	0.0001 (6)	−0.0012 (6)	−0.0022 (6)
N4	0.0100 (6)	0.0205 (7)	0.0161 (7)	0.0001 (6)	−0.0020 (6)	−0.0016 (6)
N5	0.0125 (7)	0.0223 (8)	0.0216 (8)	0.0002 (6)	0.0015 (7)	−0.0056 (7)
N6	0.0145 (7)	0.0240 (8)	0.0221 (9)	−0.0001 (6)	0.0015 (7)	−0.0072 (7)
C1	0.0141 (8)	0.0154 (7)	0.0147 (8)	−0.0008 (6)	0.0000 (7)	0.0013 (7)
C2	0.0133 (8)	0.0194 (8)	0.0192 (9)	−0.0028 (6)	−0.0020 (7)	−0.0022 (8)
C3	0.0118 (8)	0.0187 (8)	0.0164 (8)	−0.0010 (6)	−0.0013 (7)	−0.0003 (7)
C4	0.0160 (8)	0.0227 (9)	0.0171 (8)	0.0004 (7)	0.0022 (8)	−0.0029 (7)
C5	0.0092 (8)	0.0326 (10)	0.0263 (11)	−0.0013 (7)	−0.0008 (8)	−0.0071 (9)
C6	0.0131 (8)	0.0162 (8)	0.0125 (8)	0.0001 (6)	0.0008 (7)	−0.0003 (7)
C7	0.0149 (8)	0.0180 (8)	0.0176 (9)	0.0011 (6)	−0.0013 (7)	−0.0004 (7)

Geometric parameters (Å, º) top

O1—C7	1.215 (3)	C1—C2	1.419 (2)
N1—C1	1.332 (3)	C1—C4	1.494 (3)
N1—N2	1.381 (2)	C2—C3	1.373 (3)
N2—C3	1.382 (2)	C2—H2A	0.9500
N2—C6	1.403 (2)	C3—C5	1.494 (3)
N3—C6	1.300 (2)	C4—H4A	0.9800
N3—N4	1.334 (2)	C4—H4B	0.9800
N4—C7	1.368 (3)	C4—H4C	0.9800
N4—H4	0.89 (3)	C5—H5A	0.9800
N5—N6	1.286 (2)	C5—H5B	0.9800
N5—C6	1.377 (2)	C5—H5C	0.9800
N6—C7	1.427 (2)

C1—N1—N2	105.18 (15)	C1—C4—H4A	109.5
N1—N2—C3	111.78 (16)	C1—C4—H4B	109.5
N1—N2—C6	116.66 (14)	H4A—C4—H4B	109.5
C3—N2—C6	131.54 (16)	C1—C4—H4C	109.5
C6—N3—N4	114.58 (15)	H4A—C4—H4C	109.5
N3—N4—C7	124.80 (16)	H4B—C4—H4C	109.5
N3—N4—H4	111 (2)	C3—C5—H5A	109.5
C7—N4—H4	124 (2)	C3—C5—H5B	109.5
N6—N5—C6	118.45 (15)	H5A—C5—H5B	109.5
N5—N6—C7	120.11 (17)	C3—C5—H5C	109.5
N1—C1—C2	110.64 (17)	H5A—C5—H5C	109.5
N1—C1—C4	120.53 (17)	H5B—C5—H5C	109.5
C2—C1—C4	128.82 (17)	N3—C6—N5	125.96 (16)
C3—C2—C1	106.84 (17)	N3—C6—N2	117.11 (15)
C3—C2—H2A	126.6	N5—C6—N2	116.91 (15)
C1—C2—H2A	126.6	O1—C7—N4	123.63 (18)
C2—C3—N2	105.54 (16)	O1—C7—N6	120.87 (18)
C2—C3—C5	128.92 (17)	N4—C7—N6	115.47 (18)
N2—C3—C5	125.54 (18)

C1—N1—N2—C3	0.3 (2)	C6—N2—C3—C5	0.5 (3)
C1—N1—N2—C6	178.57 (15)	N4—N3—C6—N5	3.3 (3)
C6—N3—N4—C7	4.1 (3)	N4—N3—C6—N2	−178.47 (16)
C6—N5—N6—C7	−0.3 (3)	N6—N5—C6—N3	−5.2 (3)
N2—N1—C1—C2	0.4 (2)	N6—N5—C6—N2	176.59 (18)
N2—N1—C1—C4	−178.72 (16)	N1—N2—C6—N3	−1.0 (2)
N1—C1—C2—C3	−1.0 (2)	C3—N2—C6—N3	176.88 (19)
C4—C1—C2—C3	178.11 (19)	N1—N2—C6—N5	177.36 (16)
C1—C2—C3—N2	1.0 (2)	C3—N2—C6—N5	−4.7 (3)
C1—C2—C3—C5	−178.20 (19)	N3—N4—C7—O1	173.22 (18)
N1—N2—C3—C2	−0.8 (2)	N3—N4—C7—N6	−8.9 (3)
C6—N2—C3—C2	−178.82 (18)	N5—N6—C7—O1	−175.41 (19)
N1—N2—C3—C5	178.44 (18)	N5—N6—C7—N4	6.6 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4···N1ⁱ	0.89 (3)	2.00 (3)	2.863 (2)	161 (3)
C2—H2A···O1ⁱⁱ	0.95	2.40	3.193 (3)	141

Symmetry codes: (i) −x+2, −y+1, z+1/2; (ii) −x+3/2, y−1/2, z−3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4···N1ⁱ	0.89 (3)	2.00 (3)	2.863 (2)	161 (3)
C2—H2A···O1ⁱⁱ	0.95	2.40	3.193 (3)	141

Symmetry codes: (i) −x+2, −y+1, z+1/2; (ii) −x+3/2, y−1/2, z−3/2.

Acknowledgements

This work was supported financially by the Ministry of Education and Science of Russia through the Federal Target Program "Research and Educational Personnel of Innovative Russia at 2009–2013 Years" (grant No. 14.B37.21.0827), and, in part, by a Russian Foundation for Basic Research (grant No. 12–03-31346).

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