organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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1,4-Bis­[2-(6-bromo­hexyl)-2H-tetrazol-5-yl]­benzene

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aDepartment of Applied Science and Advanced Smart Materials Research Center, Institute of Technology, Tallaght, Dublin 24, Ireland, and bDepartment of Chemistry, University of Bath, Claverton Down, Bath BA1 7AY, England
*Correspondence e-mail: m.f.mahon@bath.ac.uk

(Received 9 November 2004; accepted 16 November 2004; online 20 November 2004)

The 150 K structure of the title compound, C20H28Br2N8, has been shown to exhibit liquid-crystal alignment in the gross array, enhanced by the presence of intermolecular Br⋯Br interactions. The asymmetric unit consists of one-half of a mol­ecule, the remainder being generated via a crystallographic inversion centre located at the centre of the benzene ring.

Comment

The synthesis of tetrazoles from the cyclo­addition reaction between an azide and a nitrile is well established (Butler, 1996[Butler, R. N. (1996). Comprehensive Heterocyclic Chemistry, Vol. 4, edited by A. R. Katrilzky, C. W. Rees & E. F. V. Scriven. Oxford: Pergamon.]). Regioselective alkyl­ation of tetrazoles has been the subject of several investigations during the last 20 years (Bethel et al., 1999[Bethel, P. A., Hill, M. S., Mahon, M. F. & Molloy, K. C. (1999). J. Chem. Soc. Perkin Trans. 1, pp. 3507-3514.]; Goodger et al., 1996[Goodger, A., Hill, M. S., Mahon, M. F., McGinley, J. & Molloy, K. C. (1996). J. Chem. Soc. Dalton Trans. pp. 847-852.]; Hill et al., 1996[Hill, M. S., Mahon, M. F., McGinley, J. & Molloy, K. C. (1996). J. Chem. Soc. Dalton Trans. pp. 835-845.]; Zubarev & Ostrovskii, 2000[Zubarev, V. Y. & Ostrovskii, V. A. (2000). Chem. Heterocycl. Compds, 53, 1421-1448.]). Our group has recently studied the alkyl­ation of 1,4-bis(1H-tetrazol-5-yl)­benzene, (I[link]), with various alkyl halides to give bifunctional products of type (II[link]) with N-2 substitution in both tetrazole rings (Fleming et al., 2004[Fleming, A. F. M., Kelleher, F., Mahon, M. F., McGinley, J. & Prajapati, V. (2004). Unpublished work.]). These compounds are intermediates in the generation of tetratetrazole macrocycles of general formula (III[link]) which include a cavity of variable dimensions tailored by both the length and flexibility of the bridging groups X and Y (Butler & NíBhrádaigh, 1994[Butler, R. N. & NíBhrádaigh, E. P. (1994). J. Chem. Res. (S), pp. 148-149.]; Butler et al., 1992[Butler, R. N., Quinn, K. F. & Welke, B. (1992). J. Chem. Soc. Chem. Commun. pp. 1481-1482.], 2001[Butler, R. N., McGinley, J., Mahon, M. F., Molloy, K. C. & NíBhrádaigh, E. P. (2001) Acta Cryst. E57, o195-o197.]; Butler & Fleming, 1997[Butler, R. N. & Fleming, A. F. M. (1997). J. Heterocycl. Chem. 34, 691-693.]). As part of our ongoing studies on this family of compounds, the structure of 1,4-bis­[2-(6-bromo­hexyl)-2H-tetrazol-5-yl]­benzene, (II[link]), is now reported (Fig. 1[link]).[link]

[Scheme 1]

The asymmetric unit consists of one half of a mol­ecule, the remainder being generated via a crystallographic inversion centre located at the centre of the benzene ring. Both tetrazole rings are coplanar with the benzene ring to which they are attached (the largest deviation from the least-squares plane is 0.023 Å for atom C4). Analysis of the gross structure reveals slipped π stacking, with a distance of 3.38 Å between the least-squares planes of the tetrazole ring and the benzene ring of its closest neighbour (Fig. 2[link]). It is also probable that liquid crystal alignment is present along the c axis in this structure, evidenced by an intermolecular distance of 3.4802 (4) Å between proximate terminal Br atoms (Fig. 3[link]). This distance is considerably shorter than twice the bromine van der Waals radius (3.90 Å) and is within the range of those values previously reported, 3.415–3.691 Å (Christofi et al., 2000[Christofi, A. M., Garratt, P. J., Hogarth, G. & Steed, J. W. (2000). J. Chem. Soc. Dalton Trans. pp. 2137-2144.]; Kuhn et al., 2004[Kuhn, N., Abu-Rayyan, A., Eichele, K., Schwarz, S. & Steimann, M. (2004). Inorg. Chim. Acta, 357, 1799-1804.]; Ruthe et al., 1997[Ruthe, F., Du Mont, W.-W. & Jones, P. G. (1997). Chem. Commun. p. 1947.]; Savinsky et al., 2001[Savinsky, R., Hopf, H., Dix, I. & Jones, P. G. (2001). Eur. J. Org. Chem. pp. 4595-4606.]).

[Figure 1]
Figure 1
Plot of the title mol­ecule. Displacement ellipsoids are drawn at the 30% probability level. Unlabelled atoms are related to labelled atoms by the symmetry operator (−x, −y, 1 − z).
[Figure 2]
Figure 2
Plot of two neighbouring mol­ecules in the crystal structure of (II[link]), showing π stacking.
[Figure 3]
Figure 3
Partial packing diagram for (II[link]), illustrating intermolecular interactions and liquid-crystal alignment.

Experimental

A suspension of 1,4-bis(1H-tetrazol-5-yl)­benzene (1.0 g, 4.7 mmol), methanol (30 ml) and triethyl­amine (1.90 g, 19 mmol) was stirred at 333 K for an hour. 1,6-Di­bromo­hexane (3.6 g, 14 mmol) was then added and the mixture was heated under reflux for 5 h. The solvent was removed and the product was purified using column chroma­tog­raphy (hexane/ethyl acetate 80/20 initially followed by 60/40). Crystals suitable for X-ray diffraction were grown from aceto­nitrile.

Crystal data
  • C20H28Br2N8

  • Mr = 540.32

  • Triclinic, [P\overline 1]

  • a = 4.6290 (1) Å

  • b = 5.7030 (1) Å

  • c = 21.7111 (6) Å

  • α = 87.494 (1)°

  • β = 85.631 (1)°

  • γ = 78.312 (2)°

  • V = 559.40 (2) Å3

  • Z = 1

  • Dx = 1.604 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 20 025reflections

  • θ = 12–18°

  • μ = 3.65 mm−1

  • T = 150 (2) K

  • Irregular tablet, colourless

  • 0.60 × 0.40 × 0.12 mm

Data collection
  • Nonius KappaCCD diffractometer

  • φ and ω scans

  • Absorption correction: multi-scan (Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-37.]) Tmin = 0.187, Tmax = 0.65

  • 8752 measured reflections

  • 3144 independent reflections

  • 2680 reflections with I > 2σ(I)

  • Rint = 0.075

  • θmax = 29.9°

  • h = −6 → 6

  • k = −7 → 7

  • l = −30 → 30

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.048

  • wR(F2) = 0.131

  • S = 1.05

  • 3144 reflections

  • 136 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0798P)2 + 0.1247P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 1.11 e Å−3

  • Δρmin = −1.18 e Å−3

H atoms were included at calculated positions and constrained to an ideal geometry, with C—H distances of 0.98 Å and with Uiso(H) = 1.2Ueq(C). The largest peak and deepest hole in the final difference map are located 849 and 0.769 Å, respectively, from atom Br1.

Data collection: COLLECT (Hooft, 1998[Hooft, R. (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: HKL DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr and R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr and R. M. Sweet, pp. 307-326. New York: Academic Press.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990[Sheldrick, G. M. (1990). Acta Cryst. A46, 467-473.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEX (McArdle, 1995[McArdle, P. (1995). J. Appl. Cryst. 28, 65.]); software used to prepare material for publication: SHELXL97.

Supporting information


Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: HKL DENZO (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEX (McArdle, 1995); software used to prepare material for publication: SHELXL97.

1,4-Bis[2-(6-bromohexyl)-2H-tetrazol-5-yl]benzene top
Crystal data top
C20H28Br2N8Z = 1
Mr = 540.32F(000) = 274
Triclinic, P1Dx = 1.604 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 4.6290 (1) ÅCell parameters from 25 reflections
b = 5.7030 (1) Åθ = 12–18°
c = 21.7110 (6) ŵ = 3.65 mm1
α = 87.494 (1)°T = 150 K
β = 85.631 (1)°Irregular tablet, colourless
γ = 78.312 (2)°0.60 × 0.40 × 0.12 mm
V = 559.40 (2) Å3
Data collection top
Nonius KappaCCD
diffractometer
3144 independent reflections
Radiation source: fine-focus sealed tube2680 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.075
KappaCCD scansθmax = 29.9°, θmin = 3.7°
Absorption correction: multi-scan
(Blessing, 1995)
h = 66
Tmin = 0.187, Tmax = 0.65k = 77
8752 measured reflectionsl = 3030
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.131H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0798P)2 + 0.1247P]
where P = (Fo2 + 2Fc2)/3
3144 reflections(Δ/σ)max = 0.001
136 parametersΔρmax = 1.11 e Å3
0 restraintsΔρmin = 1.18 e Å3
Special details top

Experimental. 'multi-scan from symmetry-related measurements (Blessing, 1995)'

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
xyzUiso*/Ueq
Br11.40358 (6)1.26534 (5)0.050985 (12)0.03308 (13)
N10.7930 (5)0.0980 (4)0.33633 (10)0.0217 (4)
N20.6453 (5)0.1849 (4)0.38397 (10)0.0217 (4)
N30.6840 (6)0.1309 (4)0.32191 (11)0.0292 (5)
N40.4560 (5)0.1999 (4)0.36189 (11)0.0273 (5)
C10.4356 (6)0.0064 (4)0.39922 (11)0.0207 (5)
C20.2114 (6)0.0045 (4)0.45048 (11)0.0206 (5)
C30.0010 (6)0.2117 (4)0.46491 (12)0.0233 (5)
H30.00040.35520.44090.028*
C40.2067 (6)0.2067 (4)0.51438 (12)0.0229 (5)
H40.34720.34820.52450.027*
C51.0312 (6)0.2472 (5)0.29910 (12)0.0246 (5)
H5A1.14720.37000.32600.030*
H5B1.16560.14670.27940.030*
C60.9040 (6)0.3692 (5)0.24945 (13)0.0252 (5)
H6A0.80350.24590.22050.030*
H6B0.75460.45600.26910.030*
C71.1433 (6)0.5451 (5)0.21343 (13)0.0243 (5)
H7A1.28590.45640.19170.029*
H7B1.25210.66220.24270.029*
C81.0156 (6)0.6788 (5)0.16645 (13)0.0252 (5)
H8A0.92350.56290.13480.030*
H8B0.85870.75410.18760.030*
C91.2497 (6)0.8726 (5)0.13441 (13)0.0256 (5)
H9A1.40960.79880.11410.031*
H9B1.33740.99210.16570.031*
C101.1181 (7)0.9966 (5)0.08686 (14)0.0318 (6)
H10A1.04770.87970.05350.038*
H10B0.94541.05600.10640.038*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0440 (2)0.02089 (17)0.03148 (19)0.00035 (12)0.00067 (12)0.00647 (11)
N10.0283 (11)0.0155 (9)0.0208 (10)0.0037 (8)0.0010 (8)0.0000 (7)
N20.0270 (11)0.0158 (9)0.0226 (10)0.0051 (8)0.0006 (8)0.0020 (7)
N30.0373 (13)0.0183 (10)0.0292 (12)0.0012 (9)0.0015 (10)0.0037 (9)
N40.0340 (13)0.0184 (10)0.0270 (11)0.0016 (9)0.0014 (9)0.0022 (8)
C10.0272 (12)0.0150 (10)0.0197 (11)0.0032 (9)0.0033 (9)0.0011 (8)
C20.0263 (12)0.0137 (10)0.0224 (11)0.0043 (8)0.0040 (9)0.0015 (8)
C30.0309 (13)0.0133 (10)0.0245 (12)0.0020 (9)0.0018 (10)0.0005 (9)
C40.0283 (13)0.0129 (10)0.0251 (12)0.0010 (9)0.0001 (9)0.0014 (8)
C50.0261 (13)0.0222 (12)0.0245 (12)0.0028 (9)0.0016 (9)0.0039 (9)
C60.0284 (13)0.0193 (11)0.0279 (13)0.0037 (9)0.0017 (10)0.0060 (9)
C70.0250 (13)0.0196 (11)0.0276 (13)0.0020 (9)0.0025 (10)0.0030 (9)
C80.0290 (13)0.0194 (11)0.0267 (13)0.0023 (9)0.0032 (10)0.0046 (9)
C90.0263 (13)0.0197 (11)0.0297 (14)0.0011 (9)0.0028 (10)0.0028 (10)
C100.0304 (14)0.0283 (14)0.0334 (15)0.0048 (11)0.0036 (11)0.0113 (11)
Geometric parameters (Å, º) top
Br1—C101.957 (3)C5—H5B0.9900
N1—N21.330 (3)C6—C71.527 (4)
N1—N31.333 (3)C6—H6A0.9900
N1—C51.462 (3)C6—H6B0.9900
N2—C11.340 (3)C7—C81.521 (4)
N3—N41.321 (3)C7—H7A0.9900
N4—C11.355 (3)C7—H7B0.9900
C1—C21.464 (4)C8—C91.532 (4)
C2—C4i1.400 (3)C8—H8A0.9900
C2—C31.401 (3)C8—H8B0.9900
C3—C41.389 (4)C9—C101.507 (4)
C3—H30.9500C9—H9A0.9900
C4—C2i1.400 (3)C9—H9B0.9900
C4—H40.9500C10—H10A0.9900
C5—C61.524 (4)C10—H10B0.9900
C5—H5A0.9900
N2—N1—N3113.8 (2)C5—C6—H6B109.2
N2—N1—C5122.8 (2)C7—C6—H6B109.2
N3—N1—C5123.1 (2)H6A—C6—H6B107.9
N1—N2—C1101.6 (2)C8—C7—C6112.2 (2)
N4—N3—N1106.2 (2)C8—C7—H7A109.2
N3—N4—C1106.1 (2)C6—C7—H7A109.2
N2—C1—N4112.3 (2)C8—C7—H7B109.2
N2—C1—C2123.4 (2)C6—C7—H7B109.2
N4—C1—C2124.3 (2)H7A—C7—H7B107.9
C4i—C2—C3119.5 (2)C7—C8—C9112.6 (2)
C4i—C2—C1119.7 (2)C7—C8—H8A109.1
C3—C2—C1120.8 (2)C9—C8—H8A109.1
C4—C3—C2119.8 (2)C7—C8—H8B109.1
C4—C3—H3120.1C9—C8—H8B109.1
C2—C3—H3120.1H8A—C8—H8B107.8
C3—C4—C2i120.7 (2)C10—C9—C8111.3 (2)
C3—C4—H4119.6C10—C9—H9A109.4
C2i—C4—H4119.6C8—C9—H9A109.4
N1—C5—C6110.2 (2)C10—C9—H9B109.4
N1—C5—H5A109.6C8—C9—H9B109.4
C6—C5—H5A109.6H9A—C9—H9B108.0
N1—C5—H5B109.6C9—C10—Br1112.1 (2)
C6—C5—H5B109.6C9—C10—H10A109.2
H5A—C5—H5B108.1Br1—C10—H10A109.2
C5—C6—C7111.9 (2)C9—C10—H10B109.2
C5—C6—H6A109.2Br1—C10—H10B109.2
C7—C6—H6A109.2H10A—C10—H10B107.9
Symmetry code: (i) x, y, z+1.
 

References

First citationBethel, P. A., Hill, M. S., Mahon, M. F. & Molloy, K. C. (1999). J. Chem. Soc. Perkin Trans. 1, pp. 3507–3514.  Web of Science CSD CrossRef Google Scholar
First citationBlessing, R. H. (1995). Acta Cryst. A51, 33–37.  CrossRef CAS Web of Science IUCr Journals Google Scholar
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First citationButler, R. N. & Fleming, A. F. M. (1997). J. Heterocycl. Chem. 34, 691–693.  CrossRef CAS Google Scholar
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First citationButler, R. N. & NíBhrádaigh, E. P. (1994). J. Chem. Res. (S), pp. 148–149.  Google Scholar
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First citationChristofi, A. M., Garratt, P. J., Hogarth, G. & Steed, J. W. (2000). J. Chem. Soc. Dalton Trans. pp. 2137–2144.  Web of Science CSD CrossRef Google Scholar
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First citationGoodger, A., Hill, M. S., Mahon, M. F., McGinley, J. & Molloy, K. C. (1996). J. Chem. Soc. Dalton Trans. pp. 847–852.  CSD CrossRef Web of Science Google Scholar
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First citationMcArdle, P. (1995). J. Appl. Cryst. 28, 65.  CrossRef IUCr Journals Google Scholar
First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr and R. M. Sweet, pp. 307–326. New York: Academic Press.  Google Scholar
First citationRuthe, F., Du Mont, W.-W. & Jones, P. G. (1997). Chem. Commun. p. 1947.  CrossRef Google Scholar
First citationSavinsky, R., Hopf, H., Dix, I. & Jones, P. G. (2001). Eur. J. Org. Chem. pp. 4595–4606.  CrossRef Google Scholar
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First citationSheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.  Google Scholar
First citationZubarev, V. Y. & Ostrovskii, V. A. (2000). Chem. Heterocycl. Compds, 53, 1421–1448.  Google Scholar

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