2-[1-(1-Naphth­yl)-1H-1,2,3-triazol-4-yl]pyridine

Happ, B.; Hoogenboom, R.; Winter, A.; Hager, M.D.; Baumann, S.O.; Kickelbick, G.; Schubert, U.S.

doi:10.1107/S160053680901407X

organic compounds

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Volume 65| Part 5| May 2009| Page o1146

doi:10.1107/S160053680901407X

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2-[1-(1-Naphthyl)-1H-1,2,3-triazol-4-yl]pyridine

Bobby Happ,^a Richard Hoogenboom,^b Andreas Winter,^b Martin D. Hager,^a Stefan O. Baumann,^c Guido Kickelbick ^c and Ulrich S. Schubert ^a,^b ^*

^aLaboratory of Organic and Macromolecular Chemistry, Friedrich-Schiller-Universität Jena, Humboldtstrasse 10, 07743 Jena, Germany, ^bEindhoven University of Technology, Laboratory of Macromolecular Chemistry and Nanoscience, Den Dolech 2, NL-5612AZ Eindhoven, The Netherlands, and ^cVienna University of Technology, Institute of Materials Chemistry, Getreidemarkt 9/165, 1060 Wien, Austria
^*Correspondence e-mail: ulrich.schubert@uni-jena.de

(Received 2 April 2009; accepted 15 April 2009; online 30 April 2009)

In the crystal structure of the title compound, C₁₇H₁₂N₄, the angle between the naphthalene and 1H-1,2,3-triazole ring systems is 71.02 (4)° and that between the pyridine and triazole rings is 8.30 (9)°.

Related literature

For related literature on the synthesis of polypyridyl ligands and 1,2,3-triazole-containing compounds, see: Marin et al. (2007 ); Winter et al. (2007 ); Balzani et al. (1996 ); Newkome et al. (2004 ); Chan et al. (2004 ); Rostovtsev et al. (2002 ); Kolb et al. (2001 ). The synthesis of the title compound is reported in Happ et al. (2009 ). For related crystal structures, see: Obata et al. (2008 ); Schweinfurth et al. (2008 ); Schulze et al. (2009 ); Li et al. (2007 ); Richardson et al. (2008 ); Angell & Burgess (2007 ).

Experimental

Crystal data

C₁₇H₁₂N₄
M_r = 272.31
Orthorhombic, P b c a
a = 11.6378 (4) Å
b = 9.3228 (4) Å
c = 25.0592 (9) Å
V = 2718.84 (18) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.63 × 0.18 × 0.07 mm

Data collection

Bruker Kappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a ) T_min = 0.950, T_max = 0.994
14517 measured reflections
2391 independent reflections
1934 reflections with I > 2σ(I)
R_int = 0.027

Refinement

R[F² > 2σ(F²)] = 0.035
wR(F²) = 0.120
S = 1.01
2391 reflections
190 parameters
H-atom parameters constrained
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: CARINE (Boudias & Monceau, 1998 ); software used to prepare material for publication: SHELXTL (Sheldrick, 2008b).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680901407X/wn2322sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053680901407X/wn2322Isup2.hkl

checkCIF report

Comment top

The development of novel functional materials for applications in solar cells or LEDs represents a major challenge in current materials science. Transition metal complexes have been investigated to extend the application possibilities in modern device technology (Marin et al., 2007; Ulbricht et al., 2009). Ru^II complexes of bipyridine-type ligands are highly interesting due to their predictable electro-optical properties (Balzani et al., 1996). The syntheses of functionalized 2,2'-bipyridines have been reviewed, revealing that the selective and easy synthesis of mono-functionalized ligands remains a synthetic challenge (Marin et al., 2007; Newkome et al., 2004). Li et al. (2007) and Obata et al. (2008) showed that the 1H-1,2,3-triazole ring system can serve as an alternative for pyridine in oligopyridine ligands. As comparable structures to 2,2':6',2''-terpyridines these examples have demonstrated the versatility of this approach to substitute pyridine rings of the oligopyridine ligands by functionalized triazoles (Schulze et al., 2009; Li et al., 2007). In order to explore the properties of such functionalized bidentate ligands, we have synthesized a library of pyridin-2-yl substituted 1H-1,2,3-triazole systems (Happ et al., 2009), utlizing the so-called Click reaction (Chan et al., 2004; Rostovtsev et al., 2002; Kolb et al., 2001) and their Ru^II complexes.

The crystal structures of 1-substituted 2-(1H-1,2,3-triazol-4-yl)pyridines have thus far been rarely discussed in the literature. The crystal structures of derivatives bearing a 4'-butyloxybenzene (Schweinfurth et al., 2008) or benzyl group (Obata et al., 2008) in the 1-position of the 1H-1,2,3-triazole ring have been reported. The structure of an unsubstituted derivative was studied by Richardson et al. (2008). Furthermore, the crystal structure of a dimeric species was discussed by Angell & Burgess (2007). The crystal structures of metal complexes of 2-(1H-1,2,3-triazol-4-yl)pyridines have been more extensively investigated. The structures of various Ru^II (Schulze et al., 2009; Li et al., 2007), Fe^II (Li et al., 2007) and Re^I complexes (Obata et al., 2008) were reported recently.

Here we report the crystal structure of the title compound. The geometric parameters are in good agreement with literature values (Schweinfurth et al., 2008). The pyridine ring and the triazole ring are nearly coplanar and the N atoms N3 and N6 show the expected anti configuration. The planes through these two heterocyclic ring systems (N1–C5 and N6–C11) deviate only by an angle of 8.30 (9)°. The naphthalene (C12–C21) and triazole (N1–C5) ring systems are inclined at an angle of 71.02 (4)°.

Related literature top

For related literature on synthetic studies, see: Marin et al. (2007); Ulbricht et al. (2009); Balzani et al. (1996); Newkome et al. (2004); Happ et al. (2009); Chan et al. (2004); Rostovtsev et al. (2002); Kolb et al. (2001). For related crystal structures, see: Obata et al. (2008); Schweinfurth et al. (2008); Schulze et al. (2009); Li et al. (2007); Richardson et al. (2008); Angell & Burgess (2007).

Experimental top

The title compound, C₁₇H₁₂N₄, was synthesized as reported previously (Happ et al., 2009): Sodium azide (6 mmol) and anhydrous CuSO₄ (62 mg, 0.4 mmol) were dissolved in dry methanol (15 ml) in a 20 ml microwave vial. (Naphthalen-1-yl)boronic acid (663 mg, 3.84 mmol) was added to the brown solution and the mixture was stirred for 17 h at room temperature. The progress of the reaction was monitored by TLC (SiO₂, CHCl₃ as eluent). Then CuSO₄.5H₂O (30 mg, 0.2 mmol), sodium ascorbate (384 mg, 1.95 mmol), 2-ethynylpyridine (435 mg, 4.2 mmol) and water (5 ml) were added. The reaction mixture was heated under microwave irradiation at 100 °C for 1 h. Water (30 ml) was added and the product was extracted with toluene (3 × 15 ml). After drying (MgSO₄) and evaporation of the solvent, the crude product was purified by column chromatography [Al₂O₃, CH₂Cl₂/EtOAc (1:1 ratio) as eluent]. The title compound was isolated as a white crystalline solid (673 mg, 64%). Single crystals of the purified compound were obtained by slow evaporation of a CH₂Cl₂/n-hexane solution (2:1 ratio).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: CARINE (Boudias & Monceau, 1998); software used to prepare material for publication: SHELXTL (Sheldrick, 2008b).

Figures top

	Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
	Fig. 2. A plot of the molecular packing of the title compound. Displacement ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.

2-[1-(1-Naphthyl)-1H-1,2,3-triazol-4-yl]pyridine top

Crystal data top

C₁₇H₁₂N₄	D_x = 1.330 Mg m⁻³
M_r = 272.31	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 4456 reflections
a = 11.6378 (4) Å	θ = 2.4–20.9°
b = 9.3228 (4) Å	µ = 0.08 mm⁻¹
c = 25.0592 (9) Å	T = 296 K
V = 2718.84 (18) Å³	Stick, colourless
Z = 8	0.63 × 0.18 × 0.07 mm
F(000) = 1136

Data collection top

Bruker Kappa APEXII diffractometer	2391 independent reflections
Radiation source: fine-focus sealed tube	1934 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.027
ω scans	θ_max = 25.0°, θ_min = 1.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a)	h = −13→13
T_min = 0.950, T_max = 0.994	k = −10→11
14517 measured reflections	l = −28→29

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.120	H-atom parameters constrained
S = 1.01	w = 1/[σ²(F_o²) + (0.0842P)² + 0.1848P] where P = (F_o² + 2F_c²)/3
2391 reflections	(Δ/σ)_max < 0.001
190 parameters	Δρ_max = 0.14 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₁₇H₁₂N₄	V = 2718.84 (18) Å³
M_r = 272.31	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 11.6378 (4) Å	µ = 0.08 mm⁻¹
b = 9.3228 (4) Å	T = 296 K
c = 25.0592 (9) Å	0.63 × 0.18 × 0.07 mm

Data collection top

Bruker Kappa APEXII diffractometer	2391 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a)	1934 reflections with I > 2σ(I)
T_min = 0.950, T_max = 0.994	R_int = 0.027
14517 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.035	0 restraints
wR(F²) = 0.120	H-atom parameters constrained
S = 1.01	Δρ_max = 0.14 e Å⁻³
2391 reflections	Δρ_min = −0.18 e Å⁻³
190 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

	x	y	z	U_iso*/U_eq
N1	0.20019 (9)	0.39250 (12)	0.37942 (4)	0.0428 (3)
N2	0.31490 (10)	0.36728 (14)	0.37933 (5)	0.0509 (3)
N3	0.35790 (10)	0.43998 (13)	0.33925 (5)	0.0489 (3)
C4	0.27219 (11)	0.51071 (14)	0.31370 (5)	0.0403 (3)
C5	0.17170 (12)	0.48053 (15)	0.33923 (5)	0.0450 (4)
H5	0.0987	0.5139	0.3306	0.054*
N6	0.19978 (11)	0.66666 (14)	0.24668 (5)	0.0530 (4)
C7	0.29352 (12)	0.60832 (15)	0.26887 (5)	0.0411 (3)
C8	0.40394 (13)	0.64153 (17)	0.25220 (5)	0.0495 (4)
H8	0.4672	0.5971	0.2678	0.059*
C9	0.41850 (15)	0.74114 (18)	0.21229 (6)	0.0590 (4)
H9	0.4918	0.7662	0.2008	0.071*
C10	0.32349 (16)	0.80283 (19)	0.18976 (7)	0.0635 (5)
H10	0.3310	0.8711	0.1629	0.076*
C11	0.21677 (15)	0.76197 (19)	0.20758 (7)	0.0619 (5)
H11	0.1526	0.8030	0.1915	0.074*
C12	0.12717 (11)	0.32768 (14)	0.41875 (5)	0.0420 (3)
C13	0.13387 (11)	0.37575 (14)	0.47248 (5)	0.0405 (3)
C14	0.20520 (12)	0.48862 (16)	0.48997 (6)	0.0482 (4)
H14	0.2525	0.5357	0.4657	0.058*
C15	0.20518 (14)	0.52911 (18)	0.54222 (7)	0.0573 (4)
H15	0.2519	0.6044	0.5532	0.069*
C16	0.13572 (14)	0.4588 (2)	0.57950 (6)	0.0607 (4)
H16	0.1381	0.4860	0.6152	0.073*
C17	0.06506 (14)	0.35138 (18)	0.56387 (6)	0.0552 (4)
H17	0.0187	0.3060	0.5890	0.066*
C18	0.06071 (12)	0.30717 (15)	0.50993 (5)	0.0445 (4)
C19	−0.01489 (14)	0.19830 (16)	0.49262 (7)	0.0554 (4)
H19	−0.0625	0.1532	0.5173	0.066*
C20	−0.01924 (15)	0.15834 (17)	0.44059 (7)	0.0587 (4)
H20	−0.0703	0.0872	0.4298	0.070*
C21	0.05301 (13)	0.22392 (16)	0.40296 (6)	0.0523 (4)
H21	0.0500	0.1963	0.3673	0.063*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0377 (6)	0.0483 (6)	0.0423 (6)	0.0049 (5)	0.0060 (5)	0.0034 (5)
N2	0.0405 (7)	0.0621 (8)	0.0501 (7)	0.0109 (6)	0.0055 (5)	0.0043 (6)
N3	0.0401 (7)	0.0593 (8)	0.0472 (7)	0.0042 (6)	0.0065 (5)	−0.0002 (6)
C4	0.0378 (7)	0.0452 (7)	0.0378 (7)	0.0007 (6)	0.0040 (5)	−0.0052 (6)
C5	0.0374 (7)	0.0524 (8)	0.0451 (8)	0.0036 (6)	0.0028 (6)	0.0066 (6)
N6	0.0468 (8)	0.0585 (8)	0.0536 (8)	0.0012 (6)	0.0035 (5)	0.0076 (6)
C7	0.0415 (8)	0.0447 (7)	0.0371 (7)	−0.0040 (6)	0.0043 (5)	−0.0063 (6)
C8	0.0425 (9)	0.0630 (9)	0.0429 (8)	−0.0055 (7)	0.0058 (6)	−0.0039 (6)
C9	0.0571 (10)	0.0706 (10)	0.0493 (9)	−0.0173 (8)	0.0161 (7)	−0.0035 (8)
C10	0.0792 (12)	0.0613 (10)	0.0500 (9)	−0.0061 (9)	0.0136 (8)	0.0087 (8)
C11	0.0632 (11)	0.0660 (10)	0.0566 (10)	0.0047 (8)	0.0022 (8)	0.0104 (8)
C12	0.0403 (7)	0.0404 (7)	0.0454 (8)	0.0062 (6)	0.0061 (6)	0.0045 (6)
C13	0.0383 (8)	0.0397 (7)	0.0437 (7)	0.0086 (6)	0.0013 (5)	0.0054 (6)
C14	0.0421 (8)	0.0502 (8)	0.0524 (9)	0.0010 (6)	0.0019 (6)	0.0040 (7)
C15	0.0517 (9)	0.0619 (10)	0.0581 (9)	0.0027 (7)	−0.0055 (7)	−0.0072 (8)
C16	0.0589 (10)	0.0774 (11)	0.0459 (9)	0.0123 (9)	−0.0010 (7)	−0.0057 (8)
C17	0.0543 (9)	0.0658 (10)	0.0455 (8)	0.0103 (8)	0.0089 (7)	0.0093 (7)
C18	0.0427 (8)	0.0440 (8)	0.0469 (8)	0.0088 (6)	0.0070 (6)	0.0089 (6)
C19	0.0540 (9)	0.0483 (8)	0.0639 (10)	−0.0024 (7)	0.0152 (7)	0.0106 (7)
C20	0.0588 (10)	0.0460 (8)	0.0713 (11)	−0.0111 (7)	0.0087 (8)	−0.0034 (8)
C21	0.0562 (9)	0.0477 (9)	0.0529 (9)	0.0017 (7)	0.0047 (7)	−0.0053 (6)

Geometric parameters (Å, º) top

N1—C5	1.3408 (17)	C12—C21	1.355 (2)
N1—N2	1.3556 (16)	C12—C13	1.4212 (19)
N1—C12	1.4348 (17)	C13—C14	1.410 (2)
N2—N3	1.3110 (16)	C13—C18	1.4195 (19)
N3—C4	1.3563 (18)	C14—C15	1.363 (2)
C4—C5	1.3623 (19)	C14—H14	0.9300
C4—C7	1.4669 (19)	C15—C16	1.398 (2)
C5—H5	0.9300	C15—H15	0.9300
N6—C11	1.337 (2)	C16—C17	1.354 (2)
N6—C7	1.3398 (19)	C16—H16	0.9300
C7—C8	1.386 (2)	C17—C18	1.414 (2)
C8—C9	1.375 (2)	C17—H17	0.9300
C8—H8	0.9300	C18—C19	1.411 (2)
C9—C10	1.368 (2)	C19—C20	1.357 (2)
C9—H9	0.9300	C19—H19	0.9300
C10—C11	1.374 (2)	C20—C21	1.403 (2)
C10—H10	0.9300	C20—H20	0.9300
C11—H11	0.9300	C21—H21	0.9300

C5—N1—N2	110.40 (11)	C13—C12—N1	119.05 (12)
C5—N1—C12	128.86 (11)	C14—C13—C12	124.20 (12)
N2—N1—C12	120.75 (11)	C14—C13—C18	118.92 (13)
N3—N2—N1	106.70 (11)	C12—C13—C18	116.84 (13)
N2—N3—C4	109.41 (11)	C15—C14—C13	120.35 (14)
N3—C4—C5	108.01 (12)	C15—C14—H14	119.8
N3—C4—C7	122.59 (12)	C13—C14—H14	119.8
C5—C4—C7	129.27 (12)	C14—C15—C16	120.81 (16)
N1—C5—C4	105.48 (12)	C14—C15—H15	119.6
N1—C5—H5	127.3	C16—C15—H15	119.6
C4—C5—H5	127.3	C17—C16—C15	120.30 (15)
C11—N6—C7	116.96 (13)	C17—C16—H16	119.9
N6—C7—C8	122.62 (13)	C15—C16—H16	119.9
N6—C7—C4	115.59 (12)	C16—C17—C18	120.93 (14)
C8—C7—C4	121.75 (13)	C16—C17—H17	119.5
C9—C8—C7	118.96 (15)	C18—C17—H17	119.5
C9—C8—H8	120.5	C19—C18—C17	121.72 (13)
C7—C8—H8	120.5	C19—C18—C13	119.63 (13)
C10—C9—C8	118.97 (15)	C17—C18—C13	118.64 (14)
C10—C9—H9	120.5	C20—C19—C18	121.07 (14)
C8—C9—H9	120.5	C20—C19—H19	119.5
C9—C10—C11	118.68 (16)	C18—C19—H19	119.5
C9—C10—H10	120.7	C19—C20—C21	120.23 (15)
C11—C10—H10	120.7	C19—C20—H20	119.9
N6—C11—C10	123.78 (16)	C21—C20—H20	119.9
N6—C11—H11	118.1	C12—C21—C20	119.76 (14)
C10—C11—H11	118.1	C12—C21—H21	120.1
C21—C12—C13	122.44 (13)	C20—C21—H21	120.1
C21—C12—N1	118.51 (13)

C5—N1—N2—N3	0.24 (15)	C5—N1—C12—C13	−109.53 (16)
C12—N1—N2—N3	179.90 (12)	N2—N1—C12—C13	70.88 (16)
N1—N2—N3—C4	−0.21 (15)	C21—C12—C13—C14	−176.38 (14)
N2—N3—C4—C5	0.12 (16)	N1—C12—C13—C14	2.65 (19)
N2—N3—C4—C7	176.41 (12)	C21—C12—C13—C18	1.60 (19)
N2—N1—C5—C4	−0.16 (15)	N1—C12—C13—C18	−179.37 (12)
C12—N1—C5—C4	−179.79 (13)	C12—C13—C14—C15	179.13 (13)
N3—C4—C5—N1	0.03 (16)	C18—C13—C14—C15	1.2 (2)
C7—C4—C5—N1	−175.93 (13)	C13—C14—C15—C16	0.7 (2)
C11—N6—C7—C8	−1.1 (2)	C14—C15—C16—C17	−1.7 (2)
C11—N6—C7—C4	176.54 (13)	C15—C16—C17—C18	0.6 (2)
N3—C4—C7—N6	177.95 (12)	C16—C17—C18—C19	−178.08 (14)
C5—C4—C7—N6	−6.6 (2)	C16—C17—C18—C13	1.3 (2)
N3—C4—C7—C8	−4.4 (2)	C14—C13—C18—C19	177.22 (13)
C5—C4—C7—C8	171.04 (14)	C12—C13—C18—C19	−0.87 (18)
N6—C7—C8—C9	1.8 (2)	C14—C13—C18—C17	−2.18 (19)
C4—C7—C8—C9	−175.67 (13)	C12—C13—C18—C17	179.73 (12)
C7—C8—C9—C10	−0.9 (2)	C17—C18—C19—C20	179.09 (14)
C8—C9—C10—C11	−0.5 (3)	C13—C18—C19—C20	−0.3 (2)
C7—N6—C11—C10	−0.5 (3)	C18—C19—C20—C21	0.8 (2)
C9—C10—C11—N6	1.3 (3)	C13—C12—C21—C20	−1.1 (2)
C5—N1—C12—C21	69.54 (19)	N1—C12—C21—C20	179.83 (13)
N2—N1—C12—C21	−110.05 (15)	C19—C20—C21—C12	−0.1 (2)

Experimental details

Crystal data
Chemical formula	C₁₇H₁₂N₄
M_r	272.31
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	296
a, b, c (Å)	11.6378 (4), 9.3228 (4), 25.0592 (9)
V (Å³)	2718.84 (18)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.63 × 0.18 × 0.07

Data collection
Diffractometer	Bruker Kappa APEXII diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2008a)
T_min, T_max	0.950, 0.994
No. of measured, independent and observed [I > 2σ(I)] reflections	14517, 2391, 1934
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.035, 0.120, 1.01
No. of reflections	2391
No. of parameters	190
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.14, −0.18

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008b), SHELXL97 (Sheldrick, 2008b), CARINE (Boudias & Monceau, 1998), SHELXTL (Sheldrick, 2008b).

Acknowledgements

This structure examination is part of ongoing work financially supported by the Dutch Polymer Institute (DPI), the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO, VICI award to USS) and the Fonds der Chemischen Industrie.

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