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ISSN: 2414-3146

2,5-Bis[(3,3,4,4,5,5,6,6,7,7,8,8,8-trideca­fluoro­oct­yl)sulfan­yl]-1,3,4-thia­diazole

aUniversity of Innsbruck, Faculty of Chemistry and Pharmacy, Innrain 80, 6020 Innsbruck, Austria
*Correspondence e-mail: schottenberger.herwig@uibk.ac.at

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 18 January 2017; accepted 22 January 2017; online 3 February 2017)

The title compound, C18H8F26N2S3, was obtained by double S-perfluoro­hexyl­ethyl­ation of dipotassium 1,3,4-thia­diazole-2,5-di­thiol­ate in methanol. The mol­ecule exhibits twofold rotational symmetry, with the S atom lying on the rotation axis. The fluoro­carbon chains adopt helical conformations and the F atoms of the two terminal C atoms are disordered over two sets of sites. No directional inter­molecular inter­actions occur in the crystal.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

The widespread use of polyfluoro­alkyl compounds (Buck et al., 2012[Buck, R. C., Murphy, P. M. & Pabon, M. (2012). Polyfluorinated Chemicals and Transformation Products, edited by T. P. Knepper & F. T. Lange, pp. 1-24. Berlin: Springer Verlag.]), e.g. as fire-fighting foams, raise questions about their impact on health. As a result of toxicological concerns, commercial production has shifted toward short-chain alternatives and new functional replacement substances (Buck, 2015[Buck, R. C. (2015). Toxicological Effects of Perfluoroalkyl and Polyfluoroalkyl Substances, edited by J. C. DeWitt, pp. 451-477. New York: Humana Press.]). The oxidation chemistry of RF-segmented sulfur compounds (Brace, 2000[Brace, N. O. (2000). J. Fluor. Chem. 105, 11-23.]), in particular the biotransformation of surfactants in the environment, is of highest relevance. Thus, the degradation of a 6:2 (perfluoro­hexyl­eth­yl) telomer thio­ether, comparable to the title compound, to sulfonate by aerobic biological oxidation is noteworthy (Harding-Marjanovic et al., 2015[Harding-Marjanovic, K. C., Houtz, E. F., Yi, S., Field, J. A., Sedlak, D. L. & Alvarez-Cohen, L. (2015). Environ. Sci. Technol. 49, 7666-7674.]). A related trideca­fluoro­octyl­thiol-derived crystal structure has been reported (Hibbert et al., 2001[Hibbert, T. G., Mahon, M. F., Molloy, K. C., Price, L. S. & Parkin, I. P. (2001). J. Mater. Chem. 11, 469-473.]). The 1,3,4-thia­diazole system is widely employed as spacer in ligands for organometallic polymers (Wang et al., 2008[Wang, Y., Shen, X., Fan, Y., Yao, H. & Hou, H. (2008). Supramol. Chem. 20, 501-515.]).

The asymmetric unit of the title compound contains one half-mol­ecule which is completed by a twofold rotation axis through the S1 atom and the midpoint of the N1—N1i bond (Fig. 1[link]). The fluoro­alkyl chains adopt a typical helical conformation (Fournier et al., 2010[Fournier, J. A., Bohn, R. K., Montgomery, J. A. & Onda, M. (2010). J. Phys. Chem. A, 114, 1118-1122.]). Positional disorder of the terminal F atoms of the fluoro tail was observed with occupancies of 0.55 and 0.45. The central 1,3,4-thia­diazole heterocycle matches in all respects the one in the known structure of 1,3,4-thia­diazole-2,5-bis­(thio­acetic acid) (Mistry et al., 2014[Mistry, J. K., Dawes, R., Choudhury, A. & Van De Mark, M. R. (2014). J. Heterocycl. Chem. 51, 747-754.]). The mol­ecular structure of the title compound is shown in Fig. 1[link]. There are no significant directed inter­molecular inter­actions. The packing of the mol­ecules is displayed in Fig. 2[link].

[Figure 1]
Figure 1
The mol­ecular structure of the title compound, showing the atom labels and 50% probability displacement ellipsoids for non-H atoms. [Symmetry code: (i) 1 − x, y, [{3\over 2}] − z.]
[Figure 2]
Figure 2
The unit cell of the title compound, viewed perpendicular to the ac plane.

Synthesis and crystallization

Dipotassium 1,3,4-thia­diazole-2,5-di­thiol­ate (2.00 g, 8.83 mmol) and 1H,1H,2H,2H-perfluoro­octyl iodide (8.53 g, 18.00 mmol) were refluxed in MeOH (20 ml) for 24 h. After cooling to room temperature, precipitation of the product was completed by addition of H2O (200 ml) and storage at 4° C for 2 h. The product was filtered off, washed with H2O (60 ml) and vacuum-dried for 24 h to yield 6.30 g (85%) of a white powder, mp. 68° C. Single crystals were obtained by slow cooling of a hot solution in MeOH.

1H NMR (300 MHz, MeOH-d4): δ 3.58–3.48 (m, 4H), 2.75 (tt, J = 17.2, 7.6 Hz, 4H) ppm IR (neat): ν 2948, 1445, 1435, 1385, 1364, 1314, 1296, 1239, 1183, 1138, 1085, 1074, 1043, 957, 913, 898, 817, 770, 743, 727, 709, 691, 636, 566, 527, 408 cm−1. FAB–MS: m/z 842.9482 (calculated 842.9507 for C18H9F26N2S3+ [M+H]+).

Refinement

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

Table 1
Experimental details

Crystal data
Chemical formula C18H8F26N2S3
Mr 842.44
Crystal system, space group Monoclinic, C2/c
Temperature (K) 176
a, b, c (Å) 41.014 (11), 5.7338 (15), 11.880 (3)
β (°) 94.442 (8)
V3) 2785.4 (13)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.46
Crystal size (mm) 0.16 × 0.12 × 0.05
 
Data collection
Diffractometer Bruker D8 QUEST PHOTON 100
Absorption correction Multi-scan (SADABS; Bruker, 2012[Bruker (2012). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.844, 0.914
No. of measured, independent and observed [I > 2σ(I)] reflections 26073, 2448, 2213
Rint 0.045
(sin θ/λ)max−1) 0.594
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.099, 1.10
No. of reflections 2448
No. of parameters 268
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.45, −0.25
Computer programs: APEX2 and SAINT (Bruker, 2012[Bruker (2012). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), XT in SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]) and Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]).

Structural data


Computing details top

Data collection: APEX2 (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: XT in SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: Mercury (Macrae et al., 2008).

2,5-Bis[(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)sulfanyl]-1,3,4-thiadiazole top
Crystal data top
C18H8F26N2S3F(000) = 1648
Mr = 842.44Dx = 2.009 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 41.014 (11) ÅCell parameters from 9946 reflections
b = 5.7338 (15) Åθ = 3.0–25.3°
c = 11.880 (3) ŵ = 0.46 mm1
β = 94.442 (8)°T = 176 K
V = 2785.4 (13) Å3Prism, colourless
Z = 40.16 × 0.12 × 0.05 mm
Data collection top
Bruker D8 QUEST PHOTON 100
diffractometer
2448 independent reflections
Radiation source: Incoatec Microfocus2213 reflections with I > 2σ(I)
Multi layered optics monochromatorRint = 0.045
Detector resolution: 10.4 pixels mm-1θmax = 25.0°, θmin = 3.0°
φ and ω scansh = 4848
Absorption correction: multi-scan
(SADABS; Bruker, 2012)
k = 66
Tmin = 0.844, Tmax = 0.914l = 1413
26073 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.037 w = 1/[σ2(Fo2) + (0.0443P)2 + 5.7325P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.099(Δ/σ)max = 0.002
S = 1.10Δρmax = 0.45 e Å3
2448 reflectionsΔρmin = 0.25 e Å3
268 parametersExtinction correction: SHELXL2014 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0025 (3)
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. Positional disorder around ratio 1:1 of fluorine atoms at the end of the C8F13-unit (F9-F13:F9A-F13A).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
S10.50001.00393 (13)0.75000.0257 (2)
S20.53603 (2)0.85182 (11)0.55112 (5)0.0335 (2)
N10.50855 (5)0.5709 (3)0.70144 (15)0.0275 (4)
C10.51458 (5)0.7812 (4)0.66790 (17)0.0230 (5)
C20.55301 (5)0.5683 (4)0.52066 (19)0.0283 (5)
H2A0.56360.49780.59030.034*
H2B0.53560.46190.48940.034*
C30.57815 (6)0.6099 (4)0.4343 (2)0.0321 (5)
H3A0.56700.67650.36460.039*
H3B0.59450.72480.46500.039*
C40.59534 (5)0.3881 (4)0.40543 (18)0.0253 (5)
C50.62393 (5)0.4299 (4)0.33031 (19)0.0269 (5)
C60.63965 (5)0.2116 (4)0.28023 (19)0.0285 (5)
C70.67203 (6)0.2533 (4)0.2252 (2)0.0324 (5)
C80.68717 (6)0.0386 (5)0.1714 (2)0.0426 (7)
C90.71765 (7)0.0801 (7)0.1079 (3)0.0549 (8)
F10.60748 (4)0.2780 (3)0.50030 (12)0.0435 (4)
F20.57418 (3)0.2354 (3)0.35119 (14)0.0485 (4)
F30.64731 (3)0.5471 (3)0.39435 (14)0.0452 (4)
F40.61347 (4)0.5721 (3)0.24509 (13)0.0509 (5)
F50.64402 (4)0.0478 (3)0.35936 (13)0.0468 (4)
F60.61772 (3)0.1280 (3)0.19835 (14)0.0530 (5)
F70.69446 (4)0.3290 (3)0.30676 (16)0.0614 (5)
F80.66726 (4)0.4198 (3)0.14744 (16)0.0605 (5)
F90.6973 (3)0.1100 (18)0.2579 (8)0.065 (3)0.55
F100.6653 (2)0.0771 (12)0.1052 (10)0.0508 (16)0.55
F110.7399 (4)0.197 (3)0.1638 (13)0.100 (5)0.55
F120.70735 (19)0.1862 (16)0.0105 (6)0.0701 (19)0.55
F130.7295 (3)0.140 (2)0.0725 (10)0.064 (2)0.55
F9A0.6907 (3)0.1311 (19)0.2408 (11)0.073 (4)0.45
F10A0.6647 (4)0.011 (2)0.0816 (14)0.118 (6)0.45
F11A0.7417 (5)0.128 (4)0.1932 (19)0.103 (7)0.45
F12A0.7178 (3)0.267 (2)0.0470 (10)0.123 (5)0.45
F13A0.7288 (4)0.072 (3)0.0679 (16)0.099 (5)0.45
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0308 (4)0.0205 (4)0.0274 (4)0.0000.0116 (3)0.000
S20.0405 (4)0.0308 (3)0.0316 (3)0.0128 (3)0.0189 (3)0.0087 (2)
N10.0332 (10)0.0249 (10)0.0254 (9)0.0026 (8)0.0083 (8)0.0001 (8)
C10.0228 (10)0.0251 (11)0.0215 (11)0.0042 (9)0.0036 (8)0.0003 (9)
C20.0244 (11)0.0299 (12)0.0313 (12)0.0049 (9)0.0065 (9)0.0025 (10)
C30.0338 (12)0.0332 (13)0.0308 (12)0.0104 (10)0.0112 (10)0.0036 (10)
C40.0232 (11)0.0289 (12)0.0235 (11)0.0013 (9)0.0008 (9)0.0005 (9)
C50.0263 (11)0.0274 (12)0.0273 (11)0.0041 (9)0.0037 (9)0.0026 (10)
C60.0284 (12)0.0280 (12)0.0298 (12)0.0004 (10)0.0060 (9)0.0009 (10)
C70.0269 (12)0.0351 (13)0.0361 (13)0.0011 (10)0.0084 (10)0.0009 (11)
C80.0363 (14)0.0461 (17)0.0465 (16)0.0037 (12)0.0115 (12)0.0092 (14)
C90.0382 (17)0.065 (2)0.064 (2)0.0098 (16)0.0215 (15)0.0073 (19)
F10.0452 (8)0.0535 (9)0.0337 (8)0.0231 (7)0.0148 (6)0.0159 (7)
F20.0269 (7)0.0560 (10)0.0642 (10)0.0092 (7)0.0126 (7)0.0264 (8)
F30.0337 (8)0.0439 (9)0.0597 (10)0.0106 (7)0.0146 (7)0.0245 (8)
F40.0621 (10)0.0533 (10)0.0404 (9)0.0282 (8)0.0241 (7)0.0215 (8)
F50.0585 (10)0.0325 (8)0.0531 (9)0.0164 (7)0.0279 (8)0.0139 (7)
F60.0294 (8)0.0730 (12)0.0569 (10)0.0064 (7)0.0040 (7)0.0358 (9)
F70.0266 (8)0.0831 (13)0.0747 (12)0.0072 (8)0.0049 (8)0.0444 (10)
F80.0641 (11)0.0496 (10)0.0729 (12)0.0147 (9)0.0373 (9)0.0276 (9)
F90.067 (4)0.079 (7)0.051 (3)0.046 (4)0.016 (3)0.027 (3)
F100.034 (3)0.047 (2)0.072 (5)0.0019 (16)0.008 (3)0.036 (2)
F110.041 (5)0.152 (13)0.111 (6)0.041 (7)0.037 (4)0.076 (9)
F120.062 (4)0.106 (5)0.047 (2)0.013 (3)0.031 (2)0.016 (3)
F130.053 (3)0.058 (6)0.083 (4)0.021 (3)0.028 (3)0.031 (3)
F9A0.081 (7)0.023 (3)0.123 (9)0.004 (4)0.064 (6)0.009 (4)
F10A0.062 (5)0.202 (14)0.086 (8)0.017 (8)0.012 (4)0.092 (10)
F11A0.033 (4)0.102 (8)0.177 (16)0.005 (5)0.025 (7)0.046 (8)
F12A0.092 (8)0.124 (9)0.166 (13)0.042 (6)0.098 (8)0.070 (8)
F13A0.102 (6)0.068 (9)0.138 (8)0.033 (5)0.078 (6)0.027 (6)
Geometric parameters (Å, º) top
S1—C1i1.741 (2)C6—F51.331 (3)
S1—C11.741 (2)C6—F61.360 (3)
S2—C11.747 (2)C6—C71.544 (3)
S2—C21.816 (2)C7—F81.332 (3)
N1—C11.300 (3)C7—F71.355 (3)
N1—N1i1.396 (4)C7—C81.540 (4)
C2—C31.529 (3)C8—F9A1.277 (12)
C2—H2A0.9900C8—F101.325 (11)
C2—H2B0.9900C8—F91.374 (9)
C3—C41.506 (3)C8—F10A1.383 (16)
C3—H3A0.9900C8—C91.528 (4)
C3—H3B0.9900C9—F13A1.108 (15)
C4—F11.353 (3)C9—F111.275 (15)
C4—F21.360 (3)C9—F12A1.293 (12)
C4—C51.546 (3)C9—F121.347 (10)
C5—F41.344 (3)C9—F11A1.38 (2)
C5—F31.355 (3)C9—F131.429 (11)
C5—C61.548 (3)
C1i—S1—C185.62 (15)F5—C6—C5109.65 (18)
C1—S2—C2100.09 (10)F6—C6—C5106.74 (18)
C1—N1—N1i111.92 (12)C7—C6—C5115.8 (2)
N1—C1—S1115.27 (16)F8—C7—F7108.8 (2)
N1—C1—S2125.32 (16)F8—C7—C8109.1 (2)
S1—C1—S2119.41 (13)F7—C7—C8106.24 (19)
C3—C2—S2106.43 (16)F8—C7—C6108.65 (19)
C3—C2—H2A110.4F7—C7—C6107.77 (19)
S2—C2—H2A110.4C8—C7—C6116.1 (2)
C3—C2—H2B110.4F10—C8—F9106.6 (7)
S2—C2—H2B110.4F9A—C8—F10A112.2 (9)
H2A—C2—H2B108.6F9A—C8—C9112.5 (7)
C4—C3—C2111.9 (2)F10—C8—C9109.2 (5)
C4—C3—H3A109.2F9—C8—C9104.7 (6)
C2—C3—H3A109.2F10A—C8—C999.9 (7)
C4—C3—H3B109.2F9A—C8—C7111.7 (6)
C2—C3—H3B109.2F10—C8—C7111.7 (4)
H3A—C3—H3B107.9F9—C8—C7107.1 (5)
F1—C4—F2105.92 (19)F10A—C8—C7102.6 (6)
F1—C4—C3110.69 (18)C9—C8—C7116.9 (3)
F2—C4—C3111.02 (18)F13A—C9—F12A113.0 (12)
F1—C4—C5107.84 (17)F11—C9—F12112.0 (10)
F2—C4—C5108.12 (18)F13A—C9—F11A100.2 (12)
C3—C4—C5112.95 (19)F12A—C9—F11A102.2 (11)
F4—C5—F3107.01 (19)F11—C9—F13111.9 (8)
F4—C5—C4108.44 (17)F12—C9—F13103.7 (6)
F3—C5—C4106.73 (17)F13A—C9—C8118.0 (10)
F4—C5—C6108.62 (18)F11—C9—C8113.8 (7)
F3—C5—C6108.63 (17)F12A—C9—C8116.4 (5)
C4—C5—C6116.98 (19)F12—C9—C8106.3 (4)
F5—C6—F6107.6 (2)F11A—C9—C8103.5 (10)
F5—C6—C7109.59 (19)F13—C9—C8108.5 (6)
F6—C6—C7107.13 (19)
Symmetry code: (i) x+1, y, z+3/2.
 

References

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