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Mol­ecules of the title compound, C4H4ClN3, are essentially planar. N—H...N hydrogen bonds link the mol­ecules into a two-dimensional network parallel to the (100) plane. The pyridazine rings of inversion-related mol­ecules are stacked with their centroids separated by a distance of 3.7597 (10) Å, indicating π–π inter­actions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807042481/ci2455sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807042481/ci2455Isup2.hkl
Contains datablock I

CCDC reference: 663692

Key indicators

  • Single-crystal X-ray study
  • T = 125 K
  • Mean [sigma](C-C)= 0.002 Å
  • R factor = 0.033
  • wR factor = 0.088
  • Data-to-parameter ratio = 16.8

checkCIF/PLATON results

No syntax errors found


No errors found in this datablock

Comment top

Pyridazines have demonstrated versatile biological activities, for example, antibacterial (Ishida et al., 1994), antidepressant (Pitarch et al., 1974) and antihypertensive (Herter et al., 1989) activities. A search of the Cambridge Structural Database (CSD, 2007 Release, Version 5.28; Allen, 2002) reveals that there are 639 crystal structures containing the pyridazine moiety. In the design of functional synthetic oligomers and ploymers, 3,6-diaminopyridazine is applied to the design of related monomeric, dimeric and trimeric duplex molecular strands (Gong et al., 2005). And in the preparation of various pyridazines, 3-amino-6-chloropyridazine is an important intermediate (Guery et al., 2001). We report here the crystal structure of the title compound.

In the title molecule (Fig. 1), the chloro and amino groups are coplanar with the pyridazine ring. Atoms N3 and Cl1 deviate from the pyridazine plane by 0.030 (1) and 0.019 (1) Å, respectively. The N1—N2 distance of 1.3548 (17) Å is slightly shorter than the N—N distance of 1.379 (2) Å reported by Gong et al. (2005).

The intermolecular N—H···N hydrogen bonds (Table 1) link the molecules into a two-dimensional network parallel to the (100) plane (Fig.2). The pyridazine rings of the inversion-related molecules at (x, y, z) and (-x, 1 - y, -z) are stacked with their centroids separated by a distance of 3.7597 (10) Å, indicating π-π interactions. In addition, C—Cl···π [Cl···pyridazine ring centroid = 3.6065 (10) Å] interactions also contribute to the stabilization of the structure.

Related literature top

For synthesis, see: Steck et al. (1954). For general background, see: Ishida et al. (1994); Pitarch et al. (1974); Herter et al. (1989); Guery et al. (2001). For related structures, see: Gong & Krische (2005). For Cambridge Structural Database (CSD), see: Allen (2002).

Experimental top

The title compound was prepared according to the literature method (Steck et al., 1954). Crystals suitable for X-ray analysis were obtained by slow evaporation of a isoproanol solution at room temperature (m.p. 483–485 K).

Refinement top

H atoms were positioned geometrically (N—H = 0.86 Å and C—H = 0.93 Å) and refined using a riding model, with Uiso(H) = 1.2–1.5Ueq(C).

Structure description top

Pyridazines have demonstrated versatile biological activities, for example, antibacterial (Ishida et al., 1994), antidepressant (Pitarch et al., 1974) and antihypertensive (Herter et al., 1989) activities. A search of the Cambridge Structural Database (CSD, 2007 Release, Version 5.28; Allen, 2002) reveals that there are 639 crystal structures containing the pyridazine moiety. In the design of functional synthetic oligomers and ploymers, 3,6-diaminopyridazine is applied to the design of related monomeric, dimeric and trimeric duplex molecular strands (Gong et al., 2005). And in the preparation of various pyridazines, 3-amino-6-chloropyridazine is an important intermediate (Guery et al., 2001). We report here the crystal structure of the title compound.

In the title molecule (Fig. 1), the chloro and amino groups are coplanar with the pyridazine ring. Atoms N3 and Cl1 deviate from the pyridazine plane by 0.030 (1) and 0.019 (1) Å, respectively. The N1—N2 distance of 1.3548 (17) Å is slightly shorter than the N—N distance of 1.379 (2) Å reported by Gong et al. (2005).

The intermolecular N—H···N hydrogen bonds (Table 1) link the molecules into a two-dimensional network parallel to the (100) plane (Fig.2). The pyridazine rings of the inversion-related molecules at (x, y, z) and (-x, 1 - y, -z) are stacked with their centroids separated by a distance of 3.7597 (10) Å, indicating π-π interactions. In addition, C—Cl···π [Cl···pyridazine ring centroid = 3.6065 (10) Å] interactions also contribute to the stabilization of the structure.

For synthesis, see: Steck et al. (1954). For general background, see: Ishida et al. (1994); Pitarch et al. (1974); Herter et al. (1989); Guery et al. (2001). For related structures, see: Gong & Krische (2005). For Cambridge Structural Database (CSD), see: Allen (2002).

Computing details top

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2002); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering.
[Figure 2] Fig. 2. The crystal packing of the title compound, viewed down the b axis. Dashed lines indicate intermolecular hydrogen bonds.
3-Amino-6-chloropyridazine top
Crystal data top
C4H4ClN3F(000) = 264
Mr = 129.55Dx = 1.609 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 1227 reflections
a = 7.5235 (14) Åθ = 2.8–27.6°
b = 6.5887 (11) ŵ = 0.59 mm1
c = 11.1748 (19) ÅT = 125 K
β = 105.045 (10)°Block, colourless
V = 534.95 (16) Å30.50 × 0.50 × 0.40 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer
1227 independent reflections
Radiation source: fine-focus sealed tube1153 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.015
φ and ω scansθmax = 27.6°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Bruker, 2002)
h = 89
Tmin = 0.756, Tmax = 0.794k = 88
5258 measured reflectionsl = 1412
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.088H-atom parameters constrained
S = 1.12 w = 1/[σ2(Fo2) + (0.047P)2 + 0.167P]
where P = (Fo2 + 2Fc2)/3
1227 reflections(Δ/σ)max = 0.001
73 parametersΔρmax = 0.25 e Å3
0 restraintsΔρmin = 0.35 e Å3
Crystal data top
C4H4ClN3V = 534.95 (16) Å3
Mr = 129.55Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.5235 (14) ŵ = 0.59 mm1
b = 6.5887 (11) ÅT = 125 K
c = 11.1748 (19) Å0.50 × 0.50 × 0.40 mm
β = 105.045 (10)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
1227 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2002)
1153 reflections with I > 2σ(I)
Tmin = 0.756, Tmax = 0.794Rint = 0.015
5258 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0330 restraints
wR(F2) = 0.088H-atom parameters constrained
S = 1.12Δρmax = 0.25 e Å3
1227 reflectionsΔρmin = 0.35 e Å3
73 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
xyzUiso*/Ueq
Cl10.34908 (6)0.22748 (6)0.47446 (3)0.04506 (16)
N10.19326 (16)0.58112 (18)0.46416 (10)0.0322 (3)
C40.17199 (19)0.7781 (2)0.63301 (12)0.0303 (3)
N30.11738 (19)0.9525 (2)0.67524 (11)0.0439 (3)
H3A0.06221.04360.62380.053*
H3B0.13770.97270.75370.053*
C20.3197 (2)0.4557 (2)0.67021 (12)0.0353 (3)
H20.38040.35200.72120.042*
C30.26466 (19)0.6271 (2)0.71699 (11)0.0341 (3)
H30.28700.64550.80210.041*
C10.28026 (18)0.4428 (2)0.54031 (12)0.0301 (3)
N20.13712 (17)0.75340 (18)0.50956 (11)0.0330 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0612 (3)0.0370 (2)0.0391 (2)0.00197 (15)0.01685 (18)0.00858 (13)
N10.0413 (6)0.0333 (6)0.0217 (5)0.0046 (5)0.0078 (4)0.0009 (4)
C40.0343 (6)0.0328 (7)0.0236 (6)0.0024 (5)0.0068 (5)0.0002 (5)
N30.0626 (8)0.0405 (7)0.0262 (6)0.0139 (6)0.0073 (5)0.0010 (5)
C20.0442 (7)0.0359 (7)0.0244 (6)0.0042 (6)0.0064 (5)0.0048 (5)
C30.0428 (7)0.0395 (7)0.0187 (5)0.0015 (6)0.0056 (5)0.0018 (5)
C10.0360 (6)0.0301 (6)0.0251 (6)0.0046 (5)0.0097 (5)0.0026 (5)
N20.0429 (6)0.0327 (6)0.0218 (5)0.0001 (4)0.0057 (5)0.0023 (4)
Geometric parameters (Å, º) top
Cl1—C11.7378 (14)N3—H3A0.86
N1—C11.3015 (18)N3—H3B0.86
N1—N21.3548 (17)C2—C31.354 (2)
C4—N21.3456 (17)C2—C11.4067 (18)
C4—N31.3460 (18)C2—H20.93
C4—C31.4204 (19)C3—H30.93
C1—N1—N2119.64 (11)C1—C2—H2121.8
N2—C4—N3117.82 (12)C2—C3—C4118.44 (12)
N2—C4—C3121.61 (12)C2—C3—H3120.8
N3—C4—C3120.57 (12)C4—C3—H3120.8
C4—N3—H3A120.0N1—C1—C2124.61 (13)
C4—N3—H3B120.0N1—C1—Cl1116.70 (10)
H3A—N3—H3B120.0C2—C1—Cl1118.69 (11)
C3—C2—C1116.44 (12)C4—N2—N1119.25 (11)
C3—C2—H2121.8
C1—C2—C3—C40.3 (2)C3—C2—C1—N11.2 (2)
N2—C4—C3—C20.6 (2)C3—C2—C1—Cl1179.46 (11)
N3—C4—C3—C2178.90 (14)N3—C4—N2—N1178.83 (12)
N2—N1—C1—C21.2 (2)C3—C4—N2—N10.6 (2)
N2—N1—C1—Cl1179.49 (9)C1—N1—N2—C40.20 (19)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3A···N2i0.862.263.1038 (18)168
N3—H3B···N1ii0.862.313.1372 (17)162
Symmetry codes: (i) x, y+2, z+1; (ii) x, y+3/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC4H4ClN3
Mr129.55
Crystal system, space groupMonoclinic, P21/c
Temperature (K)125
a, b, c (Å)7.5235 (14), 6.5887 (11), 11.1748 (19)
β (°) 105.045 (10)
V3)534.95 (16)
Z4
Radiation typeMo Kα
µ (mm1)0.59
Crystal size (mm)0.50 × 0.50 × 0.40
Data collection
DiffractometerBruker SMART CCD area-detector
Absorption correctionMulti-scan
(SADABS; Bruker, 2002)
Tmin, Tmax0.756, 0.794
No. of measured, independent and
observed [I > 2σ(I)] reflections
5258, 1227, 1153
Rint0.015
(sin θ/λ)max1)0.652
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.088, 1.12
No. of reflections1227
No. of parameters73
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.25, 0.35

Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2002), SHELXTL.

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3A···N2i0.862.263.1038 (18)168
N3—H3B···N1ii0.862.313.1372 (17)162
Symmetry codes: (i) x, y+2, z+1; (ii) x, y+3/2, z+1/2.
 

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