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

Preis, J.; Schollmeyer, D.; Detert, H.

doi:10.1107/S2414314625005668

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 10| Part 7| July 2025| x250566

https://doi.org/10.1107/S2414314625005668

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

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

^aUniversity Mainz, Duesbergweg 10-14, 55099 Mainz, Germany
^*Correspondence e-mail: [email protected]

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 17 June 2025; accepted 23 June 2025; online 11 July 2025)

Molecules of the title compound, C₁₇H₁₉ClN₄O, are essentially planar, the dihedral angles between the planes of the tetraazaindene ring system and the benzene ring and between the benzene ring and the hexyloxy chain being 1.56 (10)° and 5.02 (17)°, respectively. In the crystal, pairs of molecules are connected via π–π interactions between the phenyl ring and the triazolopyridazine moiety.

Keywords: crystal structure; heterocycles.

CCDC reference: 2466356

Structure description

The title compound (Fig. 1) was prepared in preparation for a project on discotic liquid crystals (Jochem et al., 2022 ; Rieth et al., 2020 ; Tober et al., 2019 ). Huisgen and co-workers reported the triazoloannulation to 1,3,5-triazine (Huisgen et al., 1960 ), but other chloroazines are also suitable substrates (Preis et al.; 2011 , Schollmeyer & Detert, 2014 ). Molecules of the title compound, C₁₇H₁₉N₄OCl, are almost completely planar. The tetraazaindene framework (C1–N9) is planar (r.m.s. deviation 0.0098 Å). Further minor deviations from planarity are the small dihedral angle of 1.56 (3)° between the planes of tetraazaindene and the phenyl ring and of 5.02 (3)° between phenyl ring and the planar hexyloxy chain in a perfect all-anti conformation. A small distance of 3.5056 (13) Å indicates π–π interactions between the centroids of the bicyclic unit and of the phenyl ring. These neighbouring molecules are connected via a centre of inversion. In the monoclinic unit cell, eight of the planar molecules are arranged in planes parallel to ( $[\overline{3}]$ 02) (Fig. 2).

Figure 1
View (Spek, 2009

) of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Part of the packing diagram. View along the b-axis direction (Spek, 2009

Synthesis and crystallization

A solution of 5-p-hexyloxyphenyltetrazole (200 mg) and 3,6-dichloropyrazine (60 mg) in 10 ml xylenes/pyridine (5/1) was slowly heated to reflux and stirred at this temperature for 8 d. The solution was extracted with 1 N hydrochloric acid and brine, solvents were evaporated, and the residue was purified by chromatography on silica using toluene/ethyl acetate 2/1 with 1% triethylamine as eluent. Yield: 39 mg (29%) of a brownish, crystalline solid with m.p. = 375 K. The annotation of NMR signals follows IUPAC nomenclature. ¹H-NMR (400 MHz, CDCl₃):8.36 (d, J = 9 Hz, 2 H, 2-H, 6-H ph); 8.09 (d, J = 9.6 Hz, 1H, 4-H pyridazin), 7.09 (d, J = 9.6 Hz, 1H, 5-H pyridazin), 7.03 (d, J = 9 Hz, 2 H, 3-H, 5-H ph), 4.01 (t, J = 6.6 Hz, 2 H,OCH₂), 1.83–1.76 (m, 2 H, CH₂), 1.50–1.43 (m, 2 H, CH₂), 1.36–1.31 (m, 4 H, CH₂), 0.90 (t, 3 H, CH₃); ¹³C-NMR (100 MHz, CDCl₃): 161.0 (C4 ph), 149.0 (C6 pyridazin), 148.0 (C-1 ph), 143.3 (C-3 pyridazin), 129.2 (C-2,6 ph), 126.5 (C4 pyridazin), 121.4 (C-5 pyridazin), 117.6 (C-1 ph), 114.7 (C-3,5 ph), 68.1 (OCH₂), 31.5, 25.7, 22.6, 14.0 (CH₂), 14.0 (CH₃). IR: (ATR): 3045, 2956, 2938, 2918, 2865, 1608, 1538, 1458, 1253, 1057, 830 cm⁻¹. FD—MS: 330.1 (M^+.); HR-ESI-MS: found 353.1160, calculated 3351.1145 for M+Na^+..

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₇H₁₉ClN₄O
M_r	330.81
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	193
a, b, c (Å)	21.4463 (13), 11.3646 (3), 18.0798 (11)
β (°)	130.696 (2)
V (Å³)	3341.0 (3)
Z	8
Radiation type	Cu Kα
μ (mm⁻¹)	2.10
Crystal size (mm)	0.55 × 0.45 × 0.30

Data collection
Diffractometer	Enraf–Nonius CAD-4
Absorption correction	ψ scan (Corinc; Dräger & Gattow, 1971 )
T_min, T_max	0.842, 0.996
No. of measured, independent and observed [I > 2σ(I)] reflections	3271, 3163, 2806
R_int	0.059
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.124, 1.04
No. of reflections	3163
No. of parameters	209
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.28
Computer programs: CAD-4 Software V5 (Enraf–Nonius, 1989 ), Corinc (Dräger & Gattow, 1971), SIR97 (Altomare et al., 1999 ), SHELXL2019/2 (Sheldrick, 2015 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 2466356

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314625005668/bt4176sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314625005668/bt4176Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314625005668/bt4176Isup3.cml

checkCIF report

Computing details top

6-Chloro-3-[4-(hexyloxy)phenyl]-[1,2,4]triazolo[4,3-b]pyridazine top

Crystal data top

C₁₇H₁₉ClN₄O	D_x = 1.315 Mg m⁻³
M_r = 330.81	Melting point: 375 K
Monoclinic, C2/c	Cu Kα radiation, λ = 1.54178 Å
a = 21.4463 (13) Å	Cell parameters from 25 reflections
b = 11.3646 (3) Å	θ = 65–70°
c = 18.0798 (11) Å	µ = 2.10 mm⁻¹
β = 130.696 (2)°	T = 193 K
V = 3341.0 (3) Å³	Block, light brown
Z = 8	0.55 × 0.45 × 0.30 mm
F(000) = 1392

Data collection top

Enraf–Nonius CAD-4 diffractometer	2806 reflections with I > 2σ(I)
Radiation source: rotating anode	R_int = 0.059
Graphite monochromator	θ_max = 70.0°, θ_min = 4.6°
ω/2θ scans	h = −19→26
Absorption correction: ψ scan (Corinc; Dräger & Gattow, 1971)	k = 0→13
T_min = 0.842, T_max = 0.996	l = −22→0
3271 measured reflections	3 standard reflections every 60 min
3163 independent reflections	intensity decay: 2%

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.042	H-atom parameters constrained
wR(F²) = 0.124	w = 1/[σ²(F_o²) + (0.0751P)² + 1.3637P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
3163 reflections	Δρ_max = 0.24 e Å⁻³
209 parameters	Δρ_min = −0.28 e Å⁻³
0 restraints

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Hydrogen atoms were placed at calculated positions and were refined in the riding-model approximation with C_aromatic–H = 0.95 Å and with C–H = 0.99 Å for the remaining H atoms, and with U_iso(H) = 1.5 U_eq(C_methyl) and with U_iso(H) = 1.2 U_eq(C) for the other H atoms.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cl1	0.49915 (3)	0.11106 (4)	0.10533 (3)	0.06749 (19)
C1	0.37217 (9)	0.49223 (14)	−0.07286 (11)	0.0422 (3)
N2	0.30929 (9)	0.51615 (13)	−0.16533 (10)	0.0541 (4)
N3	0.27439 (9)	0.41338 (14)	−0.21728 (11)	0.0574 (4)
C4	0.31738 (10)	0.32689 (15)	−0.15461 (12)	0.0468 (4)
C5	0.31084 (11)	0.20313 (16)	−0.16525 (13)	0.0510 (4)
H5	0.268361	0.167534	−0.226405	0.061*
C6	0.36682 (11)	0.13741 (16)	−0.08582 (13)	0.0522 (4)
H6	0.365474	0.053973	−0.089820	0.063*
C7	0.42824 (11)	0.19581 (14)	0.00451 (12)	0.0481 (4)
N8	0.43661 (8)	0.30881 (11)	0.01962 (9)	0.0428 (3)
N9	0.37955 (8)	0.37244 (11)	−0.06273 (9)	0.0398 (3)
C10	0.42205 (9)	0.58130 (13)	0.00276 (11)	0.0408 (3)
C11	0.48876 (10)	0.55610 (14)	0.09998 (12)	0.0462 (4)
H11	0.503990	0.476445	0.119914	0.055*
C12	0.53343 (10)	0.64531 (15)	0.16833 (12)	0.0476 (4)
H12	0.578976	0.626419	0.234247	0.057*
C13	0.51163 (10)	0.76159 (14)	0.14048 (12)	0.0441 (4)
C14	0.44518 (11)	0.78813 (14)	0.04373 (13)	0.0494 (4)
H14	0.430003	0.867913	0.024251	0.059*
C15	0.40134 (10)	0.70008 (14)	−0.02385 (12)	0.0476 (4)
H15	0.356206	0.719750	−0.089757	0.057*
O16	0.55092 (8)	0.85588 (10)	0.20141 (9)	0.0520 (3)
C17	0.61958 (11)	0.83485 (15)	0.30264 (12)	0.0496 (4)
H17A	0.664066	0.793793	0.309993	0.060*
H17B	0.602617	0.785342	0.331914	0.060*
C18	0.64901 (11)	0.95325 (16)	0.35216 (12)	0.0517 (4)
H18A	0.603087	0.994333	0.341648	0.062*
H18B	0.665797	1.001365	0.322062	0.062*
C19	0.72129 (11)	0.94299 (16)	0.46149 (13)	0.0513 (4)
H19A	0.702989	0.900642	0.492264	0.062*
H19B	0.765200	0.895645	0.471925	0.062*
C20	0.75647 (10)	1.06144 (16)	0.51114 (12)	0.0489 (4)
H20A	0.775972	1.102823	0.481346	0.059*
H20B	0.712101	1.109480	0.499045	0.059*
C21	0.82697 (11)	1.05264 (17)	0.62029 (13)	0.0558 (4)
H21A	0.869662	1.000154	0.632441	0.067*
H21B	0.806465	1.015937	0.650538	0.067*
C22	0.86625 (13)	1.1704 (2)	0.66969 (15)	0.0689 (6)
H22A	0.890830	1.204507	0.644107	0.103*
H22B	0.909034	1.158522	0.740232	0.103*
H22C	0.824192	1.223861	0.656558	0.103*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0834 (4)	0.0346 (2)	0.0562 (3)	0.00329 (19)	0.0331 (3)	0.00725 (17)
C1	0.0409 (8)	0.0376 (8)	0.0442 (8)	0.0017 (6)	0.0259 (7)	0.0044 (6)
N2	0.0495 (8)	0.0452 (8)	0.0473 (8)	0.0014 (6)	0.0226 (7)	0.0035 (6)
N3	0.0511 (8)	0.0510 (8)	0.0463 (8)	−0.0028 (7)	0.0213 (7)	0.0013 (6)
C4	0.0442 (8)	0.0476 (9)	0.0421 (8)	−0.0065 (7)	0.0254 (7)	−0.0027 (7)
C5	0.0532 (9)	0.0470 (9)	0.0500 (9)	−0.0121 (7)	0.0324 (8)	−0.0089 (7)
C6	0.0608 (10)	0.0381 (8)	0.0559 (10)	−0.0097 (7)	0.0373 (9)	−0.0061 (7)
C7	0.0570 (9)	0.0352 (8)	0.0504 (9)	−0.0023 (7)	0.0342 (8)	0.0021 (7)
N8	0.0469 (7)	0.0346 (7)	0.0421 (7)	0.0004 (5)	0.0270 (6)	0.0035 (5)
N9	0.0404 (6)	0.0351 (6)	0.0398 (7)	−0.0013 (5)	0.0244 (6)	0.0013 (5)
C10	0.0416 (8)	0.0338 (7)	0.0471 (8)	0.0009 (6)	0.0290 (7)	0.0023 (6)
C11	0.0490 (8)	0.0346 (8)	0.0477 (9)	0.0035 (6)	0.0283 (8)	0.0053 (6)
C12	0.0501 (9)	0.0395 (8)	0.0440 (8)	0.0023 (7)	0.0266 (8)	0.0017 (7)
C13	0.0481 (8)	0.0370 (8)	0.0504 (9)	0.0008 (6)	0.0334 (8)	−0.0008 (6)
C14	0.0531 (9)	0.0336 (8)	0.0541 (9)	0.0063 (7)	0.0317 (8)	0.0052 (7)
C15	0.0458 (8)	0.0379 (8)	0.0472 (9)	0.0047 (7)	0.0252 (7)	0.0061 (7)
O16	0.0586 (7)	0.0372 (6)	0.0490 (7)	0.0005 (5)	0.0302 (6)	−0.0034 (5)
C17	0.0540 (9)	0.0458 (9)	0.0483 (9)	0.0007 (7)	0.0331 (8)	−0.0015 (7)
C18	0.0531 (9)	0.0462 (9)	0.0514 (10)	−0.0002 (7)	0.0321 (8)	−0.0034 (7)
C19	0.0529 (9)	0.0499 (10)	0.0521 (9)	−0.0004 (8)	0.0346 (8)	0.0001 (8)
C20	0.0504 (9)	0.0496 (10)	0.0451 (9)	0.0020 (7)	0.0304 (8)	0.0015 (7)
C21	0.0532 (9)	0.0597 (11)	0.0466 (9)	0.0050 (8)	0.0290 (8)	0.0039 (8)
C22	0.0638 (12)	0.0718 (14)	0.0470 (10)	−0.0048 (10)	0.0255 (9)	−0.0034 (9)

Geometric parameters (Å, º) top

Cl1—C7	1.7169 (17)	C14—C15	1.371 (2)
C1—N2	1.322 (2)	C14—H14	0.9500
C1—N9	1.369 (2)	C15—H15	0.9500
C1—C10	1.460 (2)	O16—C17	1.435 (2)
N2—N3	1.375 (2)	C17—C18	1.508 (2)
N3—C4	1.318 (2)	C17—H17A	0.9900
C4—N9	1.384 (2)	C17—H17B	0.9900
C4—C5	1.414 (2)	C18—C19	1.526 (2)
C5—C6	1.346 (3)	C18—H18A	0.9900
C5—H5	0.9500	C18—H18B	0.9900
C6—C7	1.427 (2)	C19—C20	1.518 (2)
C6—H6	0.9500	C19—H19A	0.9900
C7—N8	1.301 (2)	C19—H19B	0.9900
N8—N9	1.3642 (18)	C20—C21	1.516 (2)
C10—C11	1.393 (2)	C20—H20A	0.9900
C10—C15	1.404 (2)	C20—H20B	0.9900
C11—C12	1.389 (2)	C21—C22	1.522 (3)
C11—H11	0.9500	C21—H21A	0.9900
C12—C13	1.383 (2)	C21—H21B	0.9900
C12—H12	0.9500	C22—H22A	0.9800
C13—O16	1.364 (2)	C22—H22B	0.9800
C13—C14	1.390 (2)	C22—H22C	0.9800

N2—C1—N9	107.90 (14)	C10—C15—H15	119.5
N2—C1—C10	124.21 (14)	C13—O16—C17	118.61 (13)
N9—C1—C10	127.88 (14)	O16—C17—C18	107.02 (14)
C1—N2—N3	109.95 (14)	O16—C17—H17A	110.3
C4—N3—N2	106.39 (13)	C18—C17—H17A	110.3
N3—C4—N9	109.83 (15)	O16—C17—H17B	110.3
N3—C4—C5	132.29 (16)	C18—C17—H17B	110.3
N9—C4—C5	117.88 (15)	H17A—C17—H17B	108.6
C6—C5—C4	117.79 (16)	C17—C18—C19	112.29 (15)
C6—C5—H5	121.1	C17—C18—H18A	109.1
C4—C5—H5	121.1	C19—C18—H18A	109.1
C5—C6—C7	118.57 (16)	C17—C18—H18B	109.1
C5—C6—H6	120.7	C19—C18—H18B	109.1
C7—C6—H6	120.7	H18A—C18—H18B	107.9
N8—C7—C6	126.68 (16)	C20—C19—C18	113.06 (15)
N8—C7—Cl1	115.18 (13)	C20—C19—H19A	109.0
C6—C7—Cl1	118.14 (13)	C18—C19—H19A	109.0
C7—N8—N9	113.04 (13)	C20—C19—H19B	109.0
N8—N9—C1	128.05 (13)	C18—C19—H19B	109.0
N8—N9—C4	126.02 (13)	H19A—C19—H19B	107.8
C1—N9—C4	105.92 (13)	C21—C20—C19	113.61 (15)
C11—C10—C15	117.73 (15)	C21—C20—H20A	108.8
C11—C10—C1	124.19 (14)	C19—C20—H20A	108.8
C15—C10—C1	118.08 (14)	C21—C20—H20B	108.8
C12—C11—C10	121.19 (15)	C19—C20—H20B	108.8
C12—C11—H11	119.4	H20A—C20—H20B	107.7
C10—C11—H11	119.4	C20—C21—C22	113.99 (16)
C13—C12—C11	120.03 (15)	C20—C21—H21A	108.8
C13—C12—H12	120.0	C22—C21—H21A	108.8
C11—C12—H12	120.0	C20—C21—H21B	108.8
O16—C13—C12	124.93 (15)	C22—C21—H21B	108.8
O16—C13—C14	115.63 (14)	H21A—C21—H21B	107.7
C12—C13—C14	119.44 (16)	C21—C22—H22A	109.5
C15—C14—C13	120.52 (15)	C21—C22—H22B	109.5
C15—C14—H14	119.7	H22A—C22—H22B	109.5
C13—C14—H14	119.7	C21—C22—H22C	109.5
C14—C15—C10	121.08 (15)	H22A—C22—H22C	109.5
C14—C15—H15	119.5	H22B—C22—H22C	109.5

N9—C1—N2—N3	0.05 (19)	N2—C1—C10—C11	−179.38 (16)
C10—C1—N2—N3	−178.86 (14)	N9—C1—C10—C11	1.9 (2)
C1—N2—N3—C4	−0.1 (2)	N2—C1—C10—C15	1.0 (2)
N2—N3—C4—N9	0.12 (19)	N9—C1—C10—C15	−177.68 (15)
N2—N3—C4—C5	−179.79 (18)	C15—C10—C11—C12	−0.1 (2)
N3—C4—C5—C6	178.23 (18)	C1—C10—C11—C12	−179.74 (15)
N9—C4—C5—C6	−1.7 (2)	C10—C11—C12—C13	0.4 (3)
C4—C5—C6—C7	1.2 (2)	C11—C12—C13—O16	179.81 (15)
C5—C6—C7—N8	0.2 (3)	C11—C12—C13—C14	−0.4 (3)
C5—C6—C7—Cl1	179.87 (14)	O16—C13—C14—C15	179.88 (15)
C6—C7—N8—N9	−1.0 (2)	C12—C13—C14—C15	0.0 (3)
Cl1—C7—N8—N9	179.28 (10)	C13—C14—C15—C10	0.3 (3)
C7—N8—N9—C1	−178.30 (15)	C11—C10—C15—C14	−0.2 (2)
C7—N8—N9—C4	0.5 (2)	C1—C10—C15—C14	179.43 (15)
N2—C1—N9—N8	179.00 (14)	C12—C13—O16—C17	−0.9 (2)
C10—C1—N9—N8	−2.1 (3)	C14—C13—O16—C17	179.32 (14)
N2—C1—N9—C4	0.02 (17)	C13—O16—C17—C18	−178.57 (13)
C10—C1—N9—C4	178.88 (15)	O16—C17—C18—C19	178.74 (13)
N3—C4—N9—N8	−179.09 (14)	C17—C18—C19—C20	175.09 (14)
C5—C4—N9—N8	0.8 (2)	C18—C19—C20—C21	178.53 (15)
N3—C4—N9—C1	−0.09 (18)	C19—C20—C21—C22	176.26 (17)
C5—C4—N9—C1	179.84 (15)

References

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