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The title compound, C18H16Cl2N4O, was prepared from isobutyric anhydride and 3,6-bis­(4-chloro­phen­yl)-1,2-dihydro-1,2,4,5-tetra­zine. The central six-membered ring has a boat conformation.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805018519/dn6225sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536805018519/dn6225Isup2.hkl
Contains datablock I

CCDC reference: 287547

Key indicators

  • Single-crystal X-ray study
  • T = 298 K
  • Mean [sigma](C-C) = 0.009 Å
  • R factor = 0.040
  • wR factor = 0.122
  • Data-to-parameter ratio = 8.8

checkCIF/PLATON results

No syntax errors found




Alert level B PLAT031_ALERT_4_B Refined Extinction Parameter within Range ...... 1.89 Sigma PLAT242_ALERT_2_B Check Low Ueq as Compared to Neighbors for C16
Alert level C PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low .... 42 Perc. PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ? PLAT220_ALERT_2_C Large Non-Solvent C Ueq(max)/Ueq(min) ... 2.56 Ratio PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C8 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C11 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C14 PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ... 9 PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 1 C18 H16 Cl2 N4 O
Alert level G REFLT03_ALERT_4_G WARNING: Large fraction of Friedel related reflns may be needed to determine absolute structure From the CIF: _diffrn_reflns_theta_max 25.17 From the CIF: _reflns_number_total 1997 Count of symmetry unique reflns 1910 Completeness (_total/calc) 104.55% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 87 Fraction of Friedel pairs measured 0.046 Are heavy atom types Z>Si present yes
0 ALERT level A = In general: serious problem 2 ALERT level B = Potentially serious problem 8 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 5 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 3 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

1,2,4,5-Tetrazine derivatives have a high potential for biological activity and possess a wide range of antiviral and antitumor properties. These derivatives have been widely used in making pesticides and herbicides (Sauer, 1996). As part of our continuing interest in the structure-activity relationship of 1,2,4,5-tetrazine derivatives (Hu et al., 2002, 2004), we have isolated the product, (I), of the reaction of isobutyric anhydride and 3,6-bis(4-chlorophenyl)-1,2-dihydro-1,2,4,5-tetrazine as yellow crystals suitable for X-ray analysis.

The molecular structure of (I) is illustrated in Fig. 1. Atoms N2, C3, N5 and C6 are coplanar, with the largest deviation from the plane being −0.024 (3) Å for atom N5. Atoms N1 and N4 deviate from this plane by 0.413 (8) and 0.344 (8) Å, respectively, indicating a boat conformation. There is an N—H···O hydrogen interactions building a zigzag chain parallel to the a axis (Table 1 and Fig. 2).

Experimental top

The title compound was prepared according to the procedure of Rao & Hu (2004). A solution of the compound in ethanol was concentrated gradually at room temperature to afford yellow prisms (m.p. 472–474 K).

Refinement top

H atoms were included in calculated positions and refined using a riding model. H atoms were given isotropic displacement parameters equal to 1.2 (or 1.5 for methyl H atoms) times the equivalent isotropic displacement parameters of their parent atoms and C—H distances were restrained to 0.93 Å for aromatic H atoms, 0.96 Å for methyl H atoms, and 0.97 Å for the remainder. N—H distances were restrained to 0.86 Å.

Although there are not sufficient Friedel pairs to determine reliably the absolute structure, the values of the Flack's parameter, 0.3 (2) for one model and 0.7 (2) for the inverted one, seems to be in favour of the initial model.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Version 1.05; Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The structure of (I), showing the atom-labelling scheme. Ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. View showing the N—H···O hydrogen bonding and the formation of the zigzag chain. For clarity, only H atoms involved in hydrogen bonding are represented. [Symmetry code: (i) x − 1/2, 1/2 − y, 1 − z.]
3,6-Bis(4-chlorophenyl)-1-isobutyryl-1,4-dihydro-1,2,4,5-tetrazine top
Crystal data top
C18H16Cl2N4ODx = 1.364 Mg m3
Mr = 375.25Melting point = 472–474 K
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 25 reflections
a = 7.268 (4) Åθ = 10.1–10.8°
b = 11.813 (1) ŵ = 0.37 mm1
c = 21.282 (3) ÅT = 298 K
V = 1827.2 (10) Å3Prismatic, yellow
Z = 40.25 × 0.25 × 0.20 mm
F(000) = 776
Data collection top
Enraf–Nonius CAD-4
diffractometer
840 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.025
Graphite monochromatorθmax = 25.2°, θmin = 1.9°
ω/2θ scansh = 08
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)
k = 014
Tmin = 0.912, Tmax = 0.930l = 125
2019 measured reflections3 standard reflections every 60 min
1997 independent reflections intensity decay: 0.3%
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.040 w = 1/[σ2(Fo2) + (0.0447P)2 + 0.4296P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.122(Δ/σ)max < 0.001
S = 0.99Δρmax = 0.21 e Å3
1997 reflectionsΔρmin = 0.21 e Å3
227 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0017 (9)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.27 (17)
Crystal data top
C18H16Cl2N4OV = 1827.2 (10) Å3
Mr = 375.25Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.268 (4) ŵ = 0.37 mm1
b = 11.813 (1) ÅT = 298 K
c = 21.282 (3) Å0.25 × 0.25 × 0.20 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
840 reflections with I > 2σ(I)
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)
Rint = 0.025
Tmin = 0.912, Tmax = 0.9303 standard reflections every 60 min
2019 measured reflections intensity decay: 0.3%
1997 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.122Δρmax = 0.21 e Å3
S = 0.99Δρmin = 0.21 e Å3
1997 reflectionsAbsolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
227 parametersAbsolute structure parameter: 0.27 (17)
0 restraints
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
C161.4950 (9)0.0440 (5)0.4576 (3)0.0628 (17)
H161.46810.01040.41650.075*
C181.6985 (10)0.0351 (7)0.4693 (4)0.116 (3)
H18A1.76380.07620.43740.174*
H18B1.72680.06640.50980.174*
H18C1.73470.04300.46820.174*
C171.4311 (12)0.1640 (5)0.4570 (3)0.115 (3)
H17A1.30240.16640.44710.173*
H17B1.45110.19710.49760.173*
H17C1.49890.20560.42600.173*
Cl10.9862 (4)0.23932 (17)0.13453 (7)0.1189 (9)
Cl20.8599 (3)0.0054 (2)0.78382 (9)0.1269 (10)
N21.1658 (7)0.0636 (4)0.42558 (19)0.0528 (13)
N41.1253 (7)0.2547 (4)0.44721 (19)0.0535 (13)
H41.15440.32140.43450.064*
O11.4435 (5)0.0319 (3)0.56104 (16)0.0576 (11)
N51.0751 (7)0.2352 (4)0.5094 (2)0.0580 (14)
C141.0869 (8)0.1838 (5)0.3401 (3)0.0455 (15)
N11.2212 (7)0.0637 (4)0.49067 (19)0.0497 (13)
C31.1268 (8)0.1641 (5)0.4067 (2)0.0472 (15)
C111.0220 (10)0.2165 (6)0.2134 (3)0.0657 (19)
C90.9997 (10)0.2792 (5)0.3189 (3)0.0678 (19)
H90.96180.33380.34760.081*
C151.3881 (10)0.0197 (5)0.5069 (3)0.0512 (16)
C61.1253 (8)0.1387 (5)0.5305 (3)0.0511 (16)
C51.0356 (9)0.1805 (6)0.6398 (3)0.0697 (19)
H51.05720.25670.63160.084*
C121.1059 (10)0.1198 (6)0.2333 (3)0.070 (2)
H121.13990.06480.20430.084*
C70.9748 (10)0.1477 (7)0.6989 (3)0.081 (2)
H70.95810.20110.73050.097*
C80.9404 (10)0.0372 (8)0.7097 (3)0.081 (2)
C131.1407 (10)0.1033 (5)0.2967 (3)0.071 (2)
H131.20050.03800.31010.086*
C21.0312 (10)0.0096 (6)0.6061 (3)0.075 (2)
H21.05360.06380.57530.090*
C41.0640 (9)0.1021 (5)0.5934 (3)0.0557 (16)
C10.9648 (10)0.0434 (6)0.6647 (3)0.086 (2)
H10.93770.11890.67270.103*
C100.9675 (11)0.2954 (5)0.2559 (3)0.080 (2)
H100.90810.36070.24240.095*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C160.065 (5)0.060 (4)0.063 (4)0.015 (4)0.007 (4)0.007 (3)
C180.065 (6)0.136 (7)0.148 (7)0.024 (5)0.007 (5)0.053 (7)
C170.144 (9)0.077 (5)0.126 (6)0.007 (6)0.008 (6)0.049 (5)
Cl10.180 (2)0.1185 (17)0.0581 (9)0.012 (2)0.0217 (15)0.0090 (11)
Cl20.1070 (17)0.202 (3)0.0716 (12)0.0083 (19)0.0134 (13)0.0428 (15)
N20.063 (3)0.052 (3)0.044 (3)0.007 (3)0.010 (3)0.007 (2)
N40.068 (3)0.042 (3)0.050 (3)0.006 (3)0.006 (3)0.006 (3)
O10.065 (3)0.049 (2)0.059 (2)0.001 (2)0.013 (2)0.001 (2)
N50.064 (4)0.057 (3)0.052 (3)0.008 (3)0.000 (3)0.003 (3)
C140.041 (4)0.043 (3)0.052 (3)0.001 (3)0.001 (3)0.001 (3)
N10.052 (3)0.053 (3)0.044 (3)0.005 (3)0.004 (3)0.002 (3)
C30.030 (3)0.055 (4)0.056 (4)0.002 (4)0.004 (3)0.006 (3)
C110.072 (5)0.075 (5)0.050 (3)0.002 (5)0.006 (4)0.002 (4)
C90.090 (5)0.057 (4)0.057 (4)0.024 (5)0.005 (4)0.006 (3)
C150.065 (5)0.038 (3)0.051 (4)0.000 (4)0.001 (4)0.001 (3)
C60.044 (4)0.059 (4)0.050 (3)0.003 (4)0.006 (4)0.003 (3)
C50.068 (5)0.083 (5)0.058 (4)0.017 (4)0.003 (4)0.001 (4)
C120.090 (5)0.068 (5)0.053 (4)0.008 (5)0.007 (4)0.009 (3)
C70.075 (5)0.109 (6)0.060 (4)0.021 (5)0.006 (4)0.004 (4)
C80.059 (5)0.122 (6)0.062 (4)0.000 (5)0.002 (4)0.026 (5)
C130.089 (5)0.063 (4)0.062 (4)0.017 (5)0.012 (4)0.009 (4)
C20.088 (5)0.082 (5)0.054 (4)0.000 (5)0.001 (4)0.007 (4)
C40.055 (4)0.060 (4)0.052 (4)0.009 (4)0.006 (3)0.001 (4)
C10.095 (6)0.089 (5)0.074 (5)0.014 (5)0.010 (5)0.012 (5)
C100.107 (6)0.060 (4)0.072 (4)0.029 (5)0.017 (5)0.004 (4)
Geometric parameters (Å, º) top
C16—C171.491 (8)N1—C151.364 (7)
C16—C181.503 (9)N1—C61.411 (7)
C16—C151.508 (7)C11—C101.358 (8)
C16—H160.9800C11—C121.362 (8)
C18—H18A0.9600C9—C101.374 (7)
C18—H18B0.9600C9—H90.9300
C18—H18C0.9600C6—C41.475 (8)
C17—H17A0.9600C5—C41.369 (7)
C17—H17B0.9600C5—C71.388 (8)
C17—H17C0.9600C5—H50.9300
Cl1—C111.721 (6)C12—C131.388 (7)
Cl2—C81.755 (6)C12—H120.9300
N2—C31.284 (6)C7—C81.349 (9)
N2—N11.443 (5)C7—H70.9300
N4—C31.375 (6)C8—C11.363 (9)
N4—N51.392 (5)C13—H130.9300
N4—H40.8600C2—C41.368 (8)
O1—C151.228 (6)C2—C11.394 (8)
N5—C61.278 (7)C2—H20.9300
C14—C91.369 (7)C1—H10.9300
C14—C131.381 (7)C10—H100.9300
C14—C31.466 (7)
C17—C16—C18112.0 (7)C14—C9—H9119.5
C17—C16—C15108.6 (5)C10—C9—H9119.5
C18—C16—C15110.9 (6)O1—C15—N1119.0 (5)
C17—C16—H16108.4O1—C15—C16122.9 (6)
C18—C16—H16108.4N1—C15—C16118.1 (5)
C15—C16—H16108.4N5—C6—N1119.4 (5)
C16—C18—H18A109.5N5—C6—C4119.6 (6)
C16—C18—H18B109.5N1—C6—C4120.6 (5)
H18A—C18—H18B109.5C4—C5—C7120.8 (6)
C16—C18—H18C109.5C4—C5—H5119.6
H18A—C18—H18C109.5C7—C5—H5119.6
H18B—C18—H18C109.5C11—C12—C13120.1 (6)
C16—C17—H17A109.5C11—C12—H12120.0
C16—C17—H17B109.5C13—C12—H12120.0
H17A—C17—H17B109.5C8—C7—C5119.0 (6)
C16—C17—H17C109.5C8—C7—H7120.5
H17A—C17—H17C109.5C5—C7—H7120.5
H17B—C17—H17C109.5C7—C8—C1122.1 (6)
C3—N2—N1111.2 (4)C7—C8—Cl2119.5 (7)
C3—N4—N5118.0 (4)C1—C8—Cl2118.4 (7)
C3—N4—H4121.0C14—C13—C12120.1 (6)
N5—N4—H4121.0C14—C13—H13119.9
C6—N5—N4114.0 (5)C12—C13—H13119.9
C9—C14—C13118.6 (5)C4—C2—C1120.9 (6)
C9—C14—C3122.7 (5)C4—C2—H2119.6
C13—C14—C3118.7 (5)C1—C2—H2119.6
C15—N1—C6121.8 (5)C2—C4—C5118.9 (6)
C15—N1—N2119.5 (5)C2—C4—C6121.0 (6)
C6—N1—N2116.0 (5)C5—C4—C6120.0 (6)
N2—C3—N4121.7 (5)C8—C1—C2118.3 (7)
N2—C3—C14119.5 (5)C8—C1—H1120.8
N4—C3—C14118.8 (5)C2—C1—H1120.8
C10—C11—C12120.0 (6)C11—C10—C9120.3 (6)
C10—C11—Cl1119.9 (6)C11—C10—H10119.9
C12—C11—Cl1120.1 (5)C9—C10—H10119.9
C14—C9—C10121.0 (6)
C3—N4—N5—C634.2 (8)C15—N1—C6—C462.2 (7)
C3—N2—N1—C15123.6 (6)N2—N1—C6—C4136.7 (5)
C3—N2—N1—C638.0 (7)C10—C11—C12—C131.9 (11)
N1—N2—C3—N45.3 (8)Cl1—C11—C12—C13177.7 (6)
N1—N2—C3—C14173.4 (5)C4—C5—C7—C81.3 (11)
N5—N4—C3—N231.7 (8)C5—C7—C8—C10.5 (12)
N5—N4—C3—C14149.7 (5)C5—C7—C8—Cl2179.0 (5)
C9—C14—C3—N2162.7 (6)C9—C14—C13—C120.2 (9)
C13—C14—C3—N217.9 (8)C3—C14—C13—C12179.6 (6)
C9—C14—C3—N418.6 (9)C11—C12—C13—C141.4 (10)
C13—C14—C3—N4160.8 (6)C1—C2—C4—C51.9 (10)
C13—C14—C9—C100.5 (10)C1—C2—C4—C6176.9 (6)
C3—C14—C9—C10178.9 (7)C7—C5—C4—C20.1 (10)
C6—N1—C15—O111.0 (8)C7—C5—C4—C6178.9 (6)
N2—N1—C15—O1171.5 (5)N5—C6—C4—C2147.1 (7)
C6—N1—C15—C16170.1 (5)N1—C6—C4—C225.8 (9)
N2—N1—C15—C169.6 (7)N5—C6—C4—C531.7 (9)
C17—C16—C15—O193.5 (7)N1—C6—C4—C5155.5 (6)
C18—C16—C15—O130.0 (8)C7—C8—C1—C21.4 (12)
C17—C16—C15—N185.4 (7)Cl2—C8—C1—C2179.1 (5)
C18—C16—C15—N1151.2 (6)C4—C2—C1—C82.7 (11)
N4—N5—C6—N10.5 (8)C12—C11—C10—C91.2 (12)
N4—N5—C6—C4173.5 (5)Cl1—C11—C10—C9178.3 (6)
C15—N1—C6—N5125.0 (6)C14—C9—C10—C110.0 (13)
N2—N1—C6—N536.2 (8)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H4···O1i0.862.322.851 (6)121
Symmetry code: (i) x1/2, y+1/2, z+1.

Experimental details

Crystal data
Chemical formulaC18H16Cl2N4O
Mr375.25
Crystal system, space groupOrthorhombic, P212121
Temperature (K)298
a, b, c (Å)7.268 (4), 11.813 (1), 21.282 (3)
V3)1827.2 (10)
Z4
Radiation typeMo Kα
µ (mm1)0.37
Crystal size (mm)0.25 × 0.25 × 0.20
Data collection
DiffractometerEnraf–Nonius CAD-4
diffractometer
Absorption correctionMulti-scan
(ABSCOR; Higashi, 1995)
Tmin, Tmax0.912, 0.930
No. of measured, independent and
observed [I > 2σ(I)] reflections
2019, 1997, 840
Rint0.025
(sin θ/λ)max1)0.598
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.122, 0.99
No. of reflections1997
No. of parameters227
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.21, 0.21
Absolute structureFlack H D (1983), Acta Cryst. A39, 876-881
Absolute structure parameter0.27 (17)

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Version 1.05; Farrugia, 1997) and PLATON (Spek, 2003), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H4···O1i0.862.322.851 (6)120.7
Symmetry code: (i) x1/2, y+1/2, z+1.
 

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