6-Chloro-3-(3-methyl­phen­yl)-1,2,4-triazolo[4,3-b]pyridazine

Jasmin Preis; Dieter Schollmeyer; Heiner Detert

doi:10.1107/S1600536811035288

. 2011 Sep 3;67(Pt 10):o2551. doi: 10.1107/S1600536811035288

6-Chloro-3-(3-methylphenyl)-1,2,4-triazolo[4,3-b]pyridazine

Jasmin Preis ^a, Dieter Schollmeyer ^a, Heiner Detert ^a,^*

PMCID: PMC3201469 PMID: 22058729

Abstract

The title compound, C₁₂H₉ClN₄, was prepared from dichloropyridazine and tolyltetrazole in a nucleophilic biaryl coupling followed by thermal ring transformation. The molecule is essentially planar (r.m.s. deviation for all non-H atoms = 0.036 Å) and an intramolecular C—H⋯N hydrogen bond occurs. In the crystal, the molecules form dimers connected via π–π interactions [centroid–centroid distance = 3.699 (2) Å], which are further connected to neighbouring molecules via C—H—N bonds. The bond lengths in the pyridazine ring system indicate a strong localization of the double bonds and there is a weak C—Cl bond [1.732 (3) Å].

Related literature

The acylation of tetrazoles with chloroazines and thermal ring transformation leads to triazolo annulated azines, see: Huisgen et al. (1961 ▶); Glang et al. (2008 ▶). For two benzo-annulated triazolopyridazines, see: Boulanger et al. (1991 ▶). For a highly phenylated triazolopyrazine, see: Kozhevnikov et al. (2005 ▶)·For the synthesis of higher conjugated and annulated heterocyclic π-systems see: Detert & Schollmeyer (1999 ▶); Sugiono & Detert (2001 ▶). For the synthesis of 1,3,4-oxadiazoles and triazoles, see: Huisgen, Sauer & Seidel (1960 ▶); Huisgen, Sturm & Markgraf (1960 ▶) and of triazolo-annulated azines, see: Preis et al. (2011 ▶).

Experimental

Crystal data

C₁₂H₉ClN₄
M _r = 244.68
Monoclinic,
a = 7.1001 (18) Å
b = 11.431 (3) Å
c = 13.783 (3) Å
β = 93.403 (6)°
V = 1116.6 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.32 mm⁻¹
T = 173 K
0.60 × 0.05 × 0.05 mm

Data collection

Bruker SMART APEXII diffractometer
14031 measured reflections
2664 independent reflections
1226 reflections with I > 2σ(I)
R _int = 0.130

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.132
S = 0.84
2664 reflections
155 parameters
H-atom parameters constrained
Δρ_max = 0.48 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811035288/bt5632sup1.cif

e-67-o2551-sup1.cif^{(16.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811035288/bt5632Isup2.hkl

e-67-o2551-Isup2.hkl^{(130.9KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811035288/bt5632Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯N9ⁱ	0.95	2.55	3.344 (4)	141
C11—H11⋯N2	0.95	2.34	3.006 (4)	127

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors are grateful to Heinz Kolshorn for the NMR spectra and invaluable discussions.

supplementary crystallographic information

Comment

The title compound was synthesized as part of a larger project focusing on the synthesis of higher conjugated and annulated heterocyclic π-systems (Detert & Schollmeyer, 1999; Sugiono & Detert, 2001). The acylation of tetrazoles followed by thermal ring transformation is a highly efficient route for the synthesis of 1,3,4-oxadiazoles and triazoles (Huisgen, Sauer & Seidel, 1960; Huisgen, Sturm & Markgraf, 1960) and can also be applied to 2-chloroazines to yield triazolo-annulated azines (Preis et al., 2011). In the crystal the title compound adopts an essentially planar structure with a dihedral angle of 2.21° between the mean planes of the phenyl ring and the bicyclic system and deviations of less than 0.01 Å from the least square plane. All torsion angles in the C—N-framework are below 2°; the torsion angle of -176.5 (3)° (C16—C12—C13—C14) results from methyl substitution. With 1.372 (3)Å (N2—N3) and 1.381 (3)Å (N8 - N9), the N—N bonds in the bicyclic framework are significantly longer than the C—N bonds C1—N2 (1.290 (4) Å), C4 - N9 (1.317 (4) Å), and C7 - N8 (1.324 (4) Å). This, the longer bonds N3—C4 (1.383 (4) Å) and N3 - C7 (1.378 (4) Å) and the alternating C—C bond lengths in the pyridazine (C4 - C5: 1.416 (4) Å; C5 - C6: 1.3435 (4) Å; C1 - C6: 1.426 (4) Å) indicate a strong localization of the double bonds. Contrary to the short bond C1 - N2 (1.290 (4) Å), the C1 - Cl1 bond (1.732 (3) Å) is long. This correlates with the reactivity of the C1—Cl1 bond, similar to an imidoyl chloride. Two molecules are connected via a center of inversion (symmetry operator: 1-x, 1-y, 1-z), by π-π-interactions and hydrogen bridging stabilize the lattice. The distances of the centroids of pyridazine and tolyl rings are only 3.70 Å and C—H—N bonds between C6—H6—N9 (H6—N9: 2.55 Å) connect the molecules.

Experimental

The title compound was prepared by adding pyridine (0.89 g, 10 mmol) to a solution of 3,6-dichloropyridazine (0.45 g, 3 mmol) and 5-(3-methyl- phenyl)tetrazole (0.96 g, 9 mmol) in toluene (15 ml). The mixture was heated to relflux for 5 h, cooled, filtered, and concentrated. The residue was purified by chromatography (SiO₂ /toluene/ethyl acetate = 1/1, R_f = 0,23). The title compound was isolated as an off-white powder with m.p. = 422 - 425 K. Crystals were obtained by slow evaporation of a solution of the title compound in chloroform/hexanes.