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2,2′-(Propane-1,3-di­yl)bis­­(2H-indazole)

aLaboratorio de Química Industrial, Centro de Laboratorios Especializados, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Pedro de Alba S/N, 66451 San Nicolás de los Garza, NL, Mexico, and bDivisión de Estudios de Posgrado, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Guerrero y Progreso S/N, Col. Treviño, 64570 Monterrey, NL, Mexico
*Correspondence e-mail: sylvain_bernes@hotmail.com

(Received 14 June 2011; accepted 18 July 2011; online 30 July 2011)

The title mol­ecule, C17H16N4, is a bis-indazole crystallized in the rare 2H-tautomeric form. Indazole heterocycles are connected by a propane C3 chain, and the mol­ecule is placed on a general position, in contrast to the analogous compound with a central C2 ethane bridge, which was previously found to be placed on an inversion center in the same space group. In the title mol­ecule, indazole rings make a dihedral angle of 60.11 (7)°, and the bridging alkyl chain displays a trans conformation, resulting in a W-shaped mol­ecule. In the crystal, mol­ecules inter­act weakly through ππ contacts between inversion-related pyrazole rings, with a centroid–centroid separation of 3.746 (2) Å.

Related literature

For the synthesis of 2H-indazoles, see: Wu et al. (2010[Wu, C., Fang, Y., Larock, R. C. & Shi, F. (2010). Org. Lett. 12, 2234-2237.]). For studies of 1H←→2H tautomerism in indazoles, see: Alkorta & Elguero (2005[Alkorta, I. & Elguero, J. (2005). J. Phys. Org. Chem. 18, 719-724.]); Yu et al. (2006[Yu, H.-Y., Li, B.-Z. & Guo, Y.-M. (2006). Chin. J. Chem. Phys. 19, 233-237.]). For 2H-indazole X-ray structures, see: Saczewski et al. (2001[Saczewski, F., Saczewski, J. & Gdaniec, M. (2001). Chem. Pharm. Bull. 49, 1203-1206.]); Rodríguez de Barbarín et al. (2006[Rodríguez de Barbarín, C., Nájera, B., Elizondo, P. & Cerda, P. (2006). Acta Cryst. E62, o5423-o5424.]); Ramos Silva et al. (2008[Ramos Silva, M., Moreira, V. M., Cardoso, C., Matos Beja, A. & Salvador, J. A. R. (2008). Acta Cryst. C64, o217-o219.]); Hurtado et al. (2009[Hurtado, J., Mac-Leod Carey, D., Muñoz-Castro, A., Arratia-Pérez, R., Quijada, R., Wu, G., Rojas, R. & Valderrama, M. (2009). J. Organomet. Chem. 694, 2636-2641.]); Zhou et al. (2010[Zhou, X., Qin, X. & Zhang, J. (2010). Acta Cryst. E66, o2732.]); Long et al. (2011[Long, L., Liu, B.-N., Liu, M. & Liu, D.-K. (2011). Acta Cryst. E67, o1546.]).

[Scheme 1]

Experimental

Crystal data
  • C17H16N4

  • Mr = 276.34

  • Orthorhombic, P b c a

  • a = 8.182 (2) Å

  • b = 10.549 (4) Å

  • c = 34.179 (9) Å

  • V = 2950.1 (16) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 298 K

  • 0.60 × 0.40 × 0.18 mm

Data collection
  • Siemens P4 diffractometer

  • 8195 measured reflections

  • 2621 independent reflections

  • 1607 reflections with I > 2σ(I)

  • Rint = 0.042

  • 3 standard reflections every 97 reflections intensity decay: 1.5%

Refinement
  • R[F2 > 2σ(F2)] = 0.049

  • wR(F2) = 0.162

  • S = 1.10

  • 2621 reflections

  • 191 parameters

  • H-atom parameters constrained

  • Δρmax = 0.20 e Å−3

  • Δρmin = −0.21 e Å−3

Data collection: XSCANS (Siemens, 1996[Siemens (1996). XSCANS. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.]); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and Mercury (Macrae et al., 2006[Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453-457.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

Although efficient synthetic routes for 2H-indazoles are available (e.g. Wu et al., 2010) few molecules belonging to this family of heterocyclic compounds have been X-ray characterized up to now. This is due, in part, to the fact that 1H tautomer for indazoles is frequently more stable than the 2H tautomer, although the opposite situation may occur for some derivatives (Alkorta & Elguero, 2005; Yu et al., 2006). On the other hand, in the case of N2-substituted indazoles, only the 2H tautomer is allowed. Tautomerism equilibrium study is important, since bioavailability and other pharmacological properties of indazoles may be dependent on such equilibria (e.g. Ramos Silva et al., 2008). Indazole derivatives have been used, for instance, for their anti-inflammatory activity.

The title compound was prepared through a three steps procedure, the key step being the cyclization of a nitroamine derivative (compound P, see Fig. 1 and Experimental). The resulting bis-indazole consists of two 2H-indazole heterocycles connected by an alkyl C3 bridge (Fig. 2). The molecule lies in a general position, in space group Pbca. It is worth noting that the analogue compound with a central C2 bridge, for which we reported the X-ray structure (Rodríguez de Barbarín et al., 2006), was found to crystallize in the same space group, although the molecule was placed on an inversion center. From this pair of structures now determined, we can propose the following general rule for n-alkyl bridged bis(2H-indazoles): even-alkyl compounds should be centrosymmetric, while odd-alkyl derivatives are expected to be non-centrosymmetric, as the title compound.

Molecular dimensions observed in the title compound compare well with those reported for other 2H-indazoles (Saczewski et al., 2001; Rodríguez de Barbarín et al., 2006; Hurtado et al., 2009; Zhou et al., 2010; Long et al., 2011). Indazole rings make a dihedral angle of 60.11 (7)°. Torsion angles N2—C8—C9—C10 and C8—C9—C10—N12, -176.7 (2) and 173.5 (2)° respectively, characterize the trans conformation for the alkyl bridge, resulting in a W-shaped molecule. The crystal structure features ππ interactions of modest strength, between molecules related by inversion (Fig. 3). The separation between the centroid of the pyrazole ring N11/N12/C11/C17/C16 and the symmetry-related centroid at position -x, 1 - y, 1 - z, is 3.746 (2) Å.

Related literature top

For the synthesis of 2H-indazoles, see: Wu et al. (2010). For studies of 1H2H tautomerism in indazoles, see: Alkorta & Elguero (2005); Yu et al. (2006). For 2H-indazole X-ray structures, see: Saczewski et al. (2001); Rodríguez de Barbarín et al. (2006); Ramos Silva et al. (2008); Hurtado et al. (2009); Zhou et al. (2010); Long et al. (2011).

Experimental top

The title ligand, PI, was obtained by a three steps reaction procedure (Fig. 1). The condensation between 1,3-diaminopropane and 2-nitrobenzaldehyde produced the corresponding imine. Selective reduction of imine bonds with sodium borohydride in methanol gave amine P, which was isolated. Then, 0.044 g of Pd/C was added to a solution of P (0.005 mol) in ethanol. This mixture was refluxed for 5.5 h, with addition of hydrazine monohydrate (0.110 mol) during the first 3 h. The mixture was filtered, distilled, and the organic phase was extracted. The product was purified by column chromatography with silica gel and ethyl acetate:hexane (2:1) as eluent. Suitable crystals were obtained by slow evaporation of an ethanol solution at 298 K. Mp 389.4–390 K; analysis found (calc. for C17H16N4): C 73.6 (73.9), H 5.8 (5.8), N 20.5% (20.3%); IR RTA: 3108 (CH Ar. νs), 2950 (–CH2νs), 1625 (C=N Ar. δs), 1514, 1467 (C=C Ar. νs and νas). 1H NMR (300 MHz, CDCl3): δ, p.p.m.: 2.73 (2H, m, –CH2–), 4.41 (4H, t, N—CH2), 7.10 (2H, dd, Ar), 7.31 (2H, dd, Ar), 7.66 (2H, dd, Ar), 7.73 (2H, td, Ar), 7.95 (2H, s, NH).

Refinement top

All H atoms were placed in idealized positions and refined as riding to their parent C atoms, with bond lengths fixed to 0.97 (methylene CH2) or 0.93 Å (aromatic CH). Isotropic displacement parameters for H atoms were calculated as Uiso(H) = 1.2 Ueq(carrier atom).

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Synthetic route for the title compound. P is the key intermediate and PI is the title compound.
[Figure 2] Fig. 2. ORTEP-like view of the title molecule, with displacement ellipsoids at the 30% probability level for non-H atoms.
[Figure 3] Fig. 3. A part of the crystal structure representing two molecules related by inversion, which interact through a ππ contact involving pyrazole rings (dashed line).
2,2'-(Propane-1,3-diyl)bis(2H-indazole) top
Crystal data top
C17H16N4Dx = 1.244 Mg m3
Mr = 276.34Melting point: 389 K
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 77 reflections
a = 8.182 (2) Åθ = 4.6–12.4°
b = 10.549 (4) ŵ = 0.08 mm1
c = 34.179 (9) ÅT = 298 K
V = 2950.1 (16) Å3Prism, yellow
Z = 80.60 × 0.40 × 0.18 mm
F(000) = 1168
Data collection top
Siemens P4
diffractometer
Rint = 0.042
Radiation source: fine-focus sealed tubeθmax = 25.1°, θmin = 2.4°
Graphite monochromatorh = 98
ω scansk = 1212
8195 measured reflectionsl = 4040
2621 independent reflections3 standard reflections every 97 reflections
1607 reflections with I > 2σ(I) intensity decay: 1.5%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.049H-atom parameters constrained
wR(F2) = 0.162 w = 1/[σ2(Fo2) + (0.0659P)2 + 0.9616P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max < 0.001
2621 reflectionsΔρmax = 0.20 e Å3
191 parametersΔρmin = 0.21 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 constraintsExtinction coefficient: 0.0159 (17)
Primary atom site location: structure-invariant direct methods
Crystal data top
C17H16N4V = 2950.1 (16) Å3
Mr = 276.34Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 8.182 (2) ŵ = 0.08 mm1
b = 10.549 (4) ÅT = 298 K
c = 34.179 (9) Å0.60 × 0.40 × 0.18 mm
Data collection top
Siemens P4
diffractometer
Rint = 0.042
8195 measured reflections3 standard reflections every 97 reflections
2621 independent reflections intensity decay: 1.5%
1607 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0490 restraints
wR(F2) = 0.162H-atom parameters constrained
S = 1.10Δρmax = 0.20 e Å3
2621 reflectionsΔρmin = 0.21 e Å3
191 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.3628 (3)0.67210 (17)0.33910 (5)0.0640 (6)
N20.2422 (2)0.75293 (17)0.34924 (5)0.0563 (5)
C10.2608 (3)0.8690 (2)0.33476 (6)0.0622 (7)
H1A0.19140.93780.33850.075*
C20.4896 (4)0.9559 (3)0.29004 (7)0.0773 (8)
H2A0.45291.03900.28760.093*
C30.6261 (5)0.9172 (3)0.27178 (8)0.0902 (10)
H3A0.68280.97440.25610.108*
C40.6856 (4)0.7935 (4)0.27562 (9)0.0986 (11)
H4A0.78150.77080.26280.118*
C50.6062 (4)0.7056 (3)0.29769 (8)0.0847 (9)
H5A0.64630.62350.30020.102*
C60.4614 (3)0.7431 (2)0.31655 (6)0.0610 (7)
C70.4032 (3)0.8675 (2)0.31308 (6)0.0604 (7)
C80.1158 (3)0.7097 (2)0.37586 (6)0.0639 (7)
H8A0.08220.62470.36860.077*
H8B0.02140.76490.37370.077*
C90.1757 (3)0.7094 (2)0.41760 (7)0.0646 (7)
H9A0.27370.65820.41950.078*
H9B0.20310.79520.42540.078*
C100.0474 (3)0.6575 (3)0.44453 (6)0.0671 (7)
H10B0.04580.71430.44470.080*
H10C0.01090.57600.43480.080*
N110.2399 (2)0.56892 (18)0.49101 (5)0.0611 (6)
N120.1075 (2)0.64232 (18)0.48438 (5)0.0571 (5)
C110.0399 (3)0.6887 (2)0.51674 (7)0.0615 (7)
H11B0.05160.74090.51810.074*
C120.1239 (4)0.6545 (2)0.58912 (7)0.0696 (7)
H12B0.04440.70400.60120.083*
C130.2351 (3)0.5902 (3)0.61062 (7)0.0699 (7)
H13B0.23060.59470.63780.084*
C140.3567 (3)0.5170 (2)0.59287 (8)0.0707 (7)
H14C0.43080.47370.60860.085*
C150.3702 (3)0.5070 (2)0.55328 (7)0.0683 (7)
H15B0.45380.46030.54180.082*
C160.2530 (3)0.5701 (2)0.53037 (6)0.0533 (6)
C170.1312 (3)0.6448 (2)0.54797 (7)0.0555 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0772 (15)0.0555 (11)0.0593 (11)0.0036 (11)0.0102 (11)0.0011 (9)
N20.0647 (13)0.0543 (10)0.0499 (10)0.0009 (10)0.0040 (10)0.0007 (8)
C10.0780 (18)0.0525 (13)0.0560 (13)0.0050 (12)0.0062 (14)0.0031 (10)
C20.107 (2)0.0695 (16)0.0558 (14)0.0202 (17)0.0037 (16)0.0056 (12)
C30.113 (3)0.095 (2)0.0633 (17)0.036 (2)0.0138 (18)0.0004 (15)
C40.100 (3)0.118 (3)0.0780 (19)0.011 (2)0.0320 (18)0.0046 (19)
C50.095 (2)0.0832 (19)0.0754 (17)0.0069 (18)0.0252 (17)0.0047 (15)
C60.0760 (17)0.0596 (14)0.0474 (12)0.0041 (13)0.0039 (12)0.0038 (10)
C70.0796 (18)0.0570 (13)0.0447 (12)0.0064 (13)0.0031 (12)0.0003 (10)
C80.0633 (16)0.0713 (15)0.0572 (13)0.0018 (13)0.0053 (12)0.0041 (11)
C90.0662 (17)0.0707 (15)0.0570 (13)0.0090 (13)0.0045 (12)0.0051 (12)
C100.0665 (17)0.0764 (16)0.0583 (14)0.0086 (14)0.0020 (13)0.0044 (12)
N110.0601 (13)0.0607 (12)0.0626 (11)0.0070 (10)0.0088 (10)0.0013 (9)
N120.0542 (12)0.0595 (11)0.0576 (11)0.0007 (10)0.0071 (10)0.0047 (9)
C110.0608 (16)0.0610 (14)0.0628 (15)0.0081 (12)0.0103 (12)0.0004 (11)
C120.0737 (18)0.0719 (16)0.0631 (15)0.0076 (15)0.0085 (14)0.0050 (12)
C130.0792 (19)0.0731 (16)0.0574 (13)0.0005 (16)0.0023 (14)0.0011 (12)
C140.0732 (19)0.0667 (15)0.0724 (16)0.0059 (14)0.0063 (14)0.0087 (13)
C150.0687 (17)0.0639 (14)0.0724 (16)0.0098 (13)0.0054 (14)0.0012 (12)
C160.0535 (14)0.0470 (11)0.0593 (13)0.0014 (11)0.0061 (11)0.0023 (10)
C170.0570 (15)0.0505 (12)0.0590 (13)0.0018 (11)0.0072 (12)0.0015 (10)
Geometric parameters (Å, º) top
N1—C61.343 (3)C9—H9A0.9700
N1—N21.350 (3)C9—H9B0.9700
N2—C11.329 (3)C10—N121.457 (3)
N2—C81.451 (3)C10—H10B0.9700
C1—C71.381 (4)C10—H10C0.9700
C1—H1A0.9300N11—C161.350 (3)
C2—C31.343 (4)N11—N121.351 (3)
C2—C71.410 (3)N12—C111.330 (3)
C2—H2A0.9300C11—C171.383 (3)
C3—C41.400 (5)C11—H11B0.9300
C3—H3A0.9300C12—C131.353 (4)
C4—C51.360 (4)C12—C171.411 (3)
C4—H4A0.9300C12—H12B0.9300
C5—C61.406 (4)C13—C141.398 (4)
C5—H5A0.9300C13—H13B0.9300
C6—C71.401 (3)C14—C151.362 (4)
C8—C91.509 (3)C14—H14C0.9300
C8—H8A0.9700C15—C161.405 (3)
C8—H8B0.9700C15—H15B0.9300
C9—C101.499 (3)C16—C171.406 (3)
C6—N1—N2103.55 (18)C10—C9—H9B109.5
C1—N2—N1113.7 (2)C8—C9—H9B109.5
C1—N2—C8127.2 (2)H9A—C9—H9B108.1
N1—N2—C8118.95 (18)N12—C10—C9112.2 (2)
N2—C1—C7106.6 (2)N12—C10—H10B109.2
N2—C1—H1A126.7C9—C10—H10B109.2
C7—C1—H1A126.7N12—C10—H10C109.2
C3—C2—C7118.4 (3)C9—C10—H10C109.2
C3—C2—H2A120.8H10B—C10—H10C107.9
C7—C2—H2A120.8C16—N11—N12103.05 (18)
C2—C3—C4121.9 (3)C11—N12—N11113.89 (19)
C2—C3—H3A119.0C11—N12—C10126.6 (2)
C4—C3—H3A119.0N11—N12—C10119.37 (19)
C5—C4—C3121.5 (3)N12—C11—C17107.1 (2)
C5—C4—H4A119.3N12—C11—H11B126.5
C3—C4—H4A119.3C17—C11—H11B126.5
C4—C5—C6117.7 (3)C13—C12—C17118.5 (2)
C4—C5—H5A121.1C13—C12—H12B120.8
C6—C5—H5A121.1C17—C12—H12B120.8
N1—C6—C7111.5 (2)C12—C13—C14121.4 (2)
N1—C6—C5127.7 (2)C12—C13—H13B119.3
C7—C6—C5120.7 (2)C14—C13—H13B119.3
C1—C7—C6104.6 (2)C15—C14—C13122.1 (2)
C1—C7—C2135.6 (3)C15—C14—H14C118.9
C6—C7—C2119.8 (3)C13—C14—H14C118.9
N2—C8—C9111.3 (2)C14—C15—C16117.5 (2)
N2—C8—H8A109.4C14—C15—H15B121.2
C9—C8—H8A109.4C16—C15—H15B121.2
N2—C8—H8B109.4N11—C16—C15127.3 (2)
C9—C8—H8B109.4N11—C16—C17112.0 (2)
H8A—C8—H8B108.0C15—C16—C17120.7 (2)
C10—C9—C8110.7 (2)C11—C17—C16103.9 (2)
C10—C9—H9A109.5C11—C17—C12136.2 (2)
C8—C9—H9A109.5C16—C17—C12119.8 (2)
C6—N1—N2—C10.6 (2)C8—C9—C10—N12173.5 (2)
C6—N1—N2—C8176.64 (19)C16—N11—N12—C110.5 (3)
N1—N2—C1—C70.3 (3)C16—N11—N12—C10176.1 (2)
C8—N2—C1—C7176.0 (2)C9—C10—N12—C11126.4 (3)
C7—C2—C3—C41.2 (4)C9—C10—N12—N1157.4 (3)
C2—C3—C4—C51.0 (5)N11—N12—C11—C170.0 (3)
C3—C4—C5—C60.2 (5)C10—N12—C11—C17176.3 (2)
N2—N1—C6—C70.6 (3)C17—C12—C13—C141.0 (4)
N2—N1—C6—C5179.3 (2)C12—C13—C14—C150.3 (4)
C4—C5—C6—N1178.9 (3)C13—C14—C15—C162.1 (4)
C4—C5—C6—C71.0 (4)N12—N11—C16—C15179.2 (2)
N2—C1—C7—C60.1 (2)N12—N11—C16—C170.8 (2)
N2—C1—C7—C2178.5 (3)C14—C15—C16—N11177.3 (2)
N1—C6—C7—C10.5 (3)C14—C15—C16—C172.7 (4)
C5—C6—C7—C1179.5 (2)N12—C11—C17—C160.5 (3)
N1—C6—C7—C2179.2 (2)N12—C11—C17—C12177.6 (3)
C5—C6—C7—C20.8 (4)N11—C16—C17—C110.8 (3)
C3—C2—C7—C1177.9 (3)C15—C16—C17—C11179.2 (2)
C3—C2—C7—C60.4 (4)N11—C16—C17—C12178.5 (2)
C1—N2—C8—C997.6 (3)C15—C16—C17—C121.5 (3)
N1—N2—C8—C977.9 (3)C13—C12—C17—C11176.4 (3)
N2—C8—C9—C10176.7 (2)C13—C12—C17—C160.4 (4)

Experimental details

Crystal data
Chemical formulaC17H16N4
Mr276.34
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)298
a, b, c (Å)8.182 (2), 10.549 (4), 34.179 (9)
V3)2950.1 (16)
Z8
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.60 × 0.40 × 0.18
Data collection
DiffractometerSiemens P4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
8195, 2621, 1607
Rint0.042
(sin θ/λ)max1)0.597
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.162, 1.10
No. of reflections2621
No. of parameters191
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.20, 0.21

Computer programs: XSCANS (Siemens, 1996), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006).

 

Acknowledgements

The authors thank the PAICyT program (Programa de Apoyo a la Investigación Científica y Tecnológica) of the Universidad Autónoma de Nuevo León for supporting this work (project No. T004–09).

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