Tris[2-(2H-indazol-2-yl)eth­yl]amine

The title tertiary amine, C₂₇H₂₇N₇, a potential tripodal ligand for coordination chemistry, crystallizes with the central N atom located on a threefold axis of a trigonal cell. The gauche conformation of the N(amime)—CH₂—CH₂—N(indazole) chain [torsion angle = −64.2 (2)°] places the pendant 2H-indazole heterocycles surrounding the symmetry axis, affording a claw-like shaped mol­ecule. Two symmetry-related indazole planes in the mol­ecule make an acute angle of 60.39 (4)°. The lone pair of the tertiary N atom is located inside the cavity, and should thus be inactive (as a ligand). In the crystal, neither significant π–π nor C—H⋯π inter­actions between molecules are found.

Related literature

For the pharmacological properties of indazoles, see: Cerecetto et al. (2005); Ryu et al. (2001); Teixeira et al. (2009). For isomerism in indazoles, see: Teixeira et al. (2006); Alkorta & Elguero (2005). For structures of related bis-(2H-indazoles), see: Rodríguez de Barbarín et al. (2006); Ovalle et al. (2011). For the structure of the precursor used in the synthesis of the title compound, see: McKee et al. (2006).

Experimental

Crystal data

• C₂₇H₂₇N₇

• M_r = 449.56

• Trigonal,

• a = 13.7314 (15) Å

• c = 22.235 (3) Å

• V = 3630.8 (8) ų

• Z = 6

• Mo Kα radiation

• μ = 0.08 mm⁻¹

• T = 130 K

• 0.40 × 0.20 × 0.20 mm

Data collection

• Oxford Diffraction Xcalibur Atlas Gemini diffractometer

• Absorption correction: multi-scan [CrysAlis PRO (Oxford Diffraction, 2009); based on expressions derived by Clark & Reid (1995)] T_min = 0.509, T_max = 1.000

• 2900 measured reflections

• 1404 independent reflections

• 852 reflections with I > 2σ(I)

• R_int = 0.035

Refinement

• R[F² > 2σ(F²)] = 0.045

• wR(F²) = 0.131

• S = 0.96

• 1404 reflections

• 103 parameters

• H-atom parameters constrained

• Δρ_max = 0.12 e Å⁻³

• Δρ_min = −0.15 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2009); cell refinement: CrysAlis RED (Oxford Diffraction, 2009); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

The interest in obtaining the title molecule, a new 2H-indazole derivative, is due to the potential applications for this class of compounds. Regarding pharmacological activity, these include anti-inflammatory, antitumor and antidepressants drugs (Cerecetto et al., 2005). These molecules have also been used in agriculture as selective herbicides (Ryu et al., 2001) and as precursors of other compounds to increase their biological activity and specificity (Teixeira et al., 2009). The chemistry of 2H-indazole remains less studied compared to its tautomer 1H-indazole, in part because the latter is thermodynamically more stable for the majority of derivatives (Teixeira et al., 2006). However the opposite situation also occurs in some cases (Alkorta & Elguero, 2005).

The title molecule is a tris-(2H-indazole) compound derived from a tertiary amine (Fig. 1). The molecule is placed on a threefold axis in space group R3 (Z' = 1/3). Each arm contains a gauche N_amime—CH₂—CH₂—N_indazole chain [torsion angle: -64.2 (2)°], forming a claw-like geometry (Fig. 2). The geometry for the tertiary N atom (N3) is consistent with the presence of the lone pair inside the molecular cavity. The three symmetry-related indazole heterocycles in the molecule are arranged in such a way that no strong interactions are present. The C1—H1A group interacts weakly with the pyrazole ring of the following arm: the separation H1A···Cgⁱ is 2.85 Å and the angle C1—H1A···Cgⁱ is 128° (Cg is the centroid of ring N1/N2/C1/C7/C6 and i stands for symmetry code: 1 - y, 1 + x-y, z). The angle between two indazole planes in the molecule is 60.39 (4)°. Other geometric parameters compare well with those previously reported for bis-(2H-indazole) compounds (Rodríguez de Barbarín et al., 2006; Ovalle et al., 2011).

Related literature

For the pharmacological properties of indazoles, see: Cerecetto et al. (2005); Ryu et al. (2001); Teixeira et al. (2009). For isomerism in indazoles, see: Teixeira et al. (2006); Alkorta & Elguero (2005). For structures of related bis-(2H-indazoles), see: Rodríguez de Barbarín et al. (2006); Ovalle et al. (2011). For the structure of the precursor used in the synthesis of the title compound, see: McKee et al. (2006).

S2. Experimental

The title molecule was obtained by a three steps reaction (Fig. 1). Condensation between tris(2-aminoethyl)amine and 2-nitrobenzaldehyde produced the corresponding tris-imine (McKee et al., 2006). Selective reduction of imine bonds with sodium borohydride in methanol gave the corresponding amine, which was isolated. Then, 0.046 g of Pd/C was added to a solution of this intermediate (0.005 mol) in ethanol. The mixture was refluxed for 4 h, with addition of hydrazine monohydrate (0.110 mol) during the first 3 h. The resulting mixture was filtered, distilled, and the organic phase was extracted. The product was purified by column chromatography with silica gel and methanol as eluent. Suitable crystals were obtained by slow evaporation of an ethanol solution at 298 K. M.p. 445 K; analysis found (calc. for C₂₇H₂₇N₇): C 71.46 (72.14), H 5.98 (6.05), N 22.56% (21.81%); IR RTA: 3119 (CH Ar. ν_s), 2953 (–CH₂– ν_s), 1623 (C=N Ar. δ_s), 1471, 1512 (C=C Ar. ν_s and ν_as). ¹H NMR (300 MHz, CDCl₃): 7.65 (d, 3H, ArH), 7.29 (t, 3H, ArH), 7.05 (t, 3H, ArH), 7.00 (d, 3H, ArH), 5.58 (s, 3H, ArH), 4.00 (t, 6H, CH₂), 3.09 (t, 6H, CH₂) p.p.m.. ¹³C NMR: 150–115 (Ar), 55–50 (–CH₂–).

S3. Refinement

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 U_iso(H) = 1.2 U_eq(carrier atom).

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2009); cell refinement: CrysAlis RED (Oxford Diffraction, 2009); data reduction: CrysAlis RED (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. Synthetic route for the title compound. The X-ray structure of the precursor [P] has been reported (McKee et al., 2006).
	Fig. 2. ORTEP-like view of the title molecule, with displacement ellipsoids at the 30% probability level for non-H atoms. Unlabeled atoms are generated by symmetry codes: -x + y, 1 - x, z and 1 - y, 1 + x-y, z. The figure on the right is a space filling representation in the same orientation, showing the full shape of the molecule.

Tris[2-(2H-indazol-2-yl)ethyl]amine

Crystal data

C27H27N7	Dx = 1.234 Mg m^−3
Mr = 449.56	Melting point: 445 K
Trigonal, R3	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -R 3	Cell parameters from 1214 reflections
a = 13.7314 (15) Å	θ = 3.5–29.5°
c = 22.235 (3) Å	µ = 0.08 mm^−1
V = 3630.8 (8) Å^3	T = 130 K
Z = 6	Plate, orange
F(000) = 1428	0.40 × 0.20 × 0.20 mm

Data collection

Oxford Diffraction Xcalibur Atlas Gemini diffractometer	1404 independent reflections
Radiation source: Enhance (Mo) X-ray Source	852 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
Detector resolution: 10.4685 pixels mm^-1	θmax = 25.3°, θmin = 3.6°
ω scans	h = −16→11
Absorption correction: multi-scan [CrysAlis PRO (Oxford Diffraction, 2009); based on expressions derived by Clark & Reid (1995)]	k = −11→16
Tmin = 0.509, Tmax = 1.000	l = −18→26
2900 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.131	H-atom parameters constrained
S = 0.96	w = 1/[σ^2(Fo^2) + (0.0792P)^2] where P = (Fo^2 + 2Fc^2)/3
1404 reflections	(Δ/σ)max < 0.001
103 parameters	Δρmax = 0.12 e Å^−3
0 restraints	Δρmin = −0.15 e Å^−3
0 constraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.06603 (12)	0.53619 (12)	0.91972 (8)	0.0708 (5)
N2	0.14166 (12)	0.50358 (11)	0.93250 (7)	0.0667 (5)
N3	0.3333	0.6667	1.01076 (10)	0.0624 (7)
C1	0.19002 (14)	0.48969 (15)	0.88423 (10)	0.0724 (6)
H1A	0.2435	0.4671	0.8839	0.087*
C2	0.16242 (17)	0.51736 (19)	0.77209 (10)	0.0881 (7)
H2A	0.2129	0.4981	0.7558	0.106*
C3	0.1031 (2)	0.54814 (19)	0.73614 (11)	0.0956 (8)
H3A	0.1128	0.5501	0.6947	0.115*
C4	0.0267 (2)	0.57740 (17)	0.76090 (12)	0.0932 (8)
H4A	−0.0127	0.5990	0.7353	0.112*
C5	0.00892 (17)	0.57496 (15)	0.82125 (12)	0.0822 (6)
H5A	−0.0423	0.5938	0.8369	0.099*
C6	0.06970 (13)	0.54348 (13)	0.85902 (10)	0.0625 (5)
C7	0.14644 (13)	0.51492 (14)	0.83448 (9)	0.0647 (5)
C8	0.15877 (17)	0.48420 (16)	0.99499 (9)	0.0802 (6)
H8A	0.2021	0.4460	0.9963	0.096*
H8B	0.0863	0.4351	1.0133	0.096*
C9	0.21862 (15)	0.59058 (16)	1.03092 (8)	0.0771 (6)
H9A	0.1761	0.6295	1.0287	0.093*
H9B	0.2206	0.5714	1.0727	0.093*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0597 (10)	0.0648 (9)	0.0921 (13)	0.0343 (8)	0.0033 (8)	0.0052 (8)
N2	0.0544 (9)	0.0587 (9)	0.0845 (12)	0.0265 (7)	−0.0009 (8)	0.0072 (7)
N3	0.0626 (10)	0.0626 (10)	0.0621 (16)	0.0313 (5)	0.000	0.000
C1	0.0472 (10)	0.0709 (12)	0.0993 (16)	0.0298 (9)	0.0048 (10)	0.0007 (10)
C2	0.0654 (13)	0.0928 (16)	0.0912 (17)	0.0283 (11)	−0.0011 (11)	−0.0138 (12)
C3	0.0872 (16)	0.0865 (16)	0.0829 (17)	0.0209 (13)	−0.0145 (13)	−0.0056 (12)
C4	0.0903 (16)	0.0622 (13)	0.110 (2)	0.0255 (12)	−0.0399 (14)	−0.0024 (12)
C5	0.0740 (13)	0.0594 (12)	0.1138 (19)	0.0338 (10)	−0.0214 (12)	−0.0076 (11)
C6	0.0464 (10)	0.0429 (9)	0.0907 (15)	0.0168 (8)	−0.0048 (9)	0.0011 (8)
C7	0.0417 (9)	0.0580 (11)	0.0835 (14)	0.0168 (8)	−0.0031 (9)	−0.0060 (9)
C8	0.0712 (13)	0.0675 (13)	0.0906 (15)	0.0262 (10)	−0.0005 (10)	0.0155 (10)
C9	0.0736 (13)	0.0812 (14)	0.0715 (14)	0.0349 (11)	0.0126 (10)	0.0132 (10)

Geometric parameters (Å, º)

N1—N2	1.351 (2)	C3—C4	1.410 (3)
N1—C6	1.353 (2)	C3—H3A	0.9300
N2—C1	1.325 (2)	C4—C5	1.361 (3)
N2—C8	1.456 (2)	C4—H4A	0.9300
N3—C9^i	1.4588 (19)	C5—C6	1.396 (3)
N3—C9	1.4588 (19)	C5—H5A	0.9300
N3—C9^ii	1.4588 (19)	C6—C7	1.405 (2)
C1—C7	1.382 (3)	C8—C9	1.499 (3)
C1—H1A	0.9300	C8—H8A	0.9700
C2—C3	1.351 (3)	C8—H8B	0.9700
C2—C7	1.402 (3)	C9—H9A	0.9700
C2—H2A	0.9300	C9—H9B	0.9700
N2—N1—C6	103.18 (13)	C4—C5—H5A	120.9
C1—N2—N1	113.64 (15)	C6—C5—H5A	120.9
C1—N2—C8	127.49 (17)	N1—C6—C5	128.11 (18)
N1—N2—C8	118.84 (15)	N1—C6—C7	111.85 (16)
C9^i—N3—C9	110.99 (10)	C5—C6—C7	120.0 (2)
C9^i—N3—C9^ii	110.99 (11)	C1—C7—C2	135.71 (19)
C9—N3—C9^ii	110.99 (11)	C1—C7—C6	103.79 (18)
N2—C1—C7	107.54 (17)	C2—C7—C6	120.51 (18)
N2—C1—H1A	126.2	N2—C8—C9	112.99 (15)
C7—C1—H1A	126.2	N2—C8—H8A	109.0
C3—C2—C7	118.8 (2)	C9—C8—H8A	109.0
C3—C2—H2A	120.6	N2—C8—H8B	109.0
C7—C2—H2A	120.6	C9—C8—H8B	109.0
C2—C3—C4	120.6 (2)	H8A—C8—H8B	107.8
C2—C3—H3A	119.7	N3—C9—C8	113.80 (16)
C4—C3—H3A	119.7	N3—C9—H9A	108.8
C5—C4—C3	121.9 (2)	C8—C9—H9A	108.8
C5—C4—H4A	119.1	N3—C9—H9B	108.8
C3—C4—H4A	119.1	C8—C9—H9B	108.8
C4—C5—C6	118.2 (2)	H9A—C9—H9B	107.7
C6—N1—N2—C1	−0.53 (18)	N2—C1—C7—C6	−0.23 (18)
C6—N1—N2—C8	−178.56 (14)	C3—C2—C7—C1	−179.5 (2)
N1—N2—C1—C7	0.49 (19)	C3—C2—C7—C6	0.3 (3)
C8—N2—C1—C7	178.32 (15)	N1—C6—C7—C1	−0.10 (18)
C7—C2—C3—C4	0.1 (3)	C5—C6—C7—C1	179.66 (15)
C2—C3—C4—C5	−0.6 (3)	N1—C6—C7—C2	−179.97 (14)
C3—C4—C5—C6	0.7 (3)	C5—C6—C7—C2	−0.2 (2)
N2—N1—C6—C5	−179.36 (16)	C1—N2—C8—C9	111.2 (2)
N2—N1—C6—C7	0.37 (18)	N1—N2—C8—C9	−71.1 (2)
C4—C5—C6—N1	179.45 (17)	C9^i—N3—C9—C8	159.04 (17)
C4—C5—C6—C7	−0.3 (2)	C9^ii—N3—C9—C8	−77.0 (3)
N2—C1—C7—C2	179.62 (19)	N2—C8—C9—N3	−64.2 (2)

Symmetry codes: (i) −x+y, −x+1, z; (ii) −y+1, x−y+1, z.