organic compounds
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
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.
Keywords: crystal structure; polyfluoro; thiadiazole.
CCDC reference: 1528993
Structure description
The widespread use of polyfluoroalkyl compounds (Buck et al., 2012), 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). The oxidation chemistry of RF-segmented sulfur compounds (Brace, 2000), in particular the biotransformation of surfactants in the environment, is of highest relevance. Thus, the degradation of a 6:2 (perfluorohexylethyl) thioether, comparable to the title compound, to sulfonate by aerobic biological oxidation is noteworthy (Harding-Marjanovic et al., 2015). A related tridecafluorooctylthiol-derived has been reported (Hibbert et al., 2001). The 1,3,4-thiadiazole system is widely employed as spacer in ligands for organometallic polymers (Wang et al., 2008).
The i bond (Fig. 1). The fluoroalkyl chains adopt a typical helical conformation (Fournier et al., 2010). 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). The molecular structure of the title compound is shown in Fig. 1. There are no significant directed intermolecular interactions. The packing of the molecules is displayed in Fig. 2.
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—N1Synthesis 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 .
details are summarized in Table 1Structural data
CCDC reference: 1528993
https://doi.org/10.1107/S2414314617001109/hb4113sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617001109/hb4113Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314617001109/hb4113Isup3.mol
Supporting information file. DOI: https://doi.org/10.1107/S2414314617001109/hb4113Isup4.cml
Data collection: APEX2 (Bruker, 2012); cell
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).C18H8F26N2S3 | F(000) = 1648 |
Mr = 842.44 | Dx = 2.009 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 41.014 (11) Å | Cell parameters from 9946 reflections |
b = 5.7338 (15) Å | θ = 3.0–25.3° |
c = 11.880 (3) Å | µ = 0.46 mm−1 |
β = 94.442 (8)° | T = 176 K |
V = 2785.4 (13) Å3 | Prism, colourless |
Z = 4 | 0.16 × 0.12 × 0.05 mm |
Bruker D8 QUEST PHOTON 100 diffractometer | 2448 independent reflections |
Radiation source: Incoatec Microfocus | 2213 reflections with I > 2σ(I) |
Multi layered optics monochromator | Rint = 0.045 |
Detector resolution: 10.4 pixels mm-1 | θmax = 25.0°, θmin = 3.0° |
φ and ω scans | h = −48→48 |
Absorption correction: multi-scan (SADABS; Bruker, 2012) | k = −6→6 |
Tmin = 0.844, Tmax = 0.914 | l = −14→13 |
26073 measured reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-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 = 1.10 | Δρmax = 0.45 e Å−3 |
2448 reflections | Δρmin = −0.25 e Å−3 |
268 parameters | Extinction correction: SHELXL2014 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0025 (3) |
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). |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
S1 | 0.5000 | 1.00393 (13) | 0.7500 | 0.0257 (2) | |
S2 | 0.53603 (2) | 0.85182 (11) | 0.55112 (5) | 0.0335 (2) | |
N1 | 0.50855 (5) | 0.5709 (3) | 0.70144 (15) | 0.0275 (4) | |
C1 | 0.51458 (5) | 0.7812 (4) | 0.66790 (17) | 0.0230 (5) | |
C2 | 0.55301 (5) | 0.5683 (4) | 0.52066 (19) | 0.0283 (5) | |
H2A | 0.5636 | 0.4978 | 0.5903 | 0.034* | |
H2B | 0.5356 | 0.4619 | 0.4894 | 0.034* | |
C3 | 0.57815 (6) | 0.6099 (4) | 0.4343 (2) | 0.0321 (5) | |
H3A | 0.5670 | 0.6765 | 0.3646 | 0.039* | |
H3B | 0.5945 | 0.7248 | 0.4650 | 0.039* | |
C4 | 0.59534 (5) | 0.3881 (4) | 0.40543 (18) | 0.0253 (5) | |
C5 | 0.62393 (5) | 0.4299 (4) | 0.33031 (19) | 0.0269 (5) | |
C6 | 0.63965 (5) | 0.2116 (4) | 0.28023 (19) | 0.0285 (5) | |
C7 | 0.67203 (6) | 0.2533 (4) | 0.2252 (2) | 0.0324 (5) | |
C8 | 0.68717 (6) | 0.0386 (5) | 0.1714 (2) | 0.0426 (7) | |
C9 | 0.71765 (7) | 0.0801 (7) | 0.1079 (3) | 0.0549 (8) | |
F1 | 0.60748 (4) | 0.2780 (3) | 0.50030 (12) | 0.0435 (4) | |
F2 | 0.57418 (3) | 0.2354 (3) | 0.35119 (14) | 0.0485 (4) | |
F3 | 0.64731 (3) | 0.5471 (3) | 0.39435 (14) | 0.0452 (4) | |
F4 | 0.61347 (4) | 0.5721 (3) | 0.24509 (13) | 0.0509 (5) | |
F5 | 0.64402 (4) | 0.0478 (3) | 0.35936 (13) | 0.0468 (4) | |
F6 | 0.61772 (3) | 0.1280 (3) | 0.19835 (14) | 0.0530 (5) | |
F7 | 0.69446 (4) | 0.3290 (3) | 0.30676 (16) | 0.0614 (5) | |
F8 | 0.66726 (4) | 0.4198 (3) | 0.14744 (16) | 0.0605 (5) | |
F9 | 0.6973 (3) | −0.1100 (18) | 0.2579 (8) | 0.065 (3) | 0.55 |
F10 | 0.6653 (2) | −0.0771 (12) | 0.1052 (10) | 0.0508 (16) | 0.55 |
F11 | 0.7399 (4) | 0.197 (3) | 0.1638 (13) | 0.100 (5) | 0.55 |
F12 | 0.70735 (19) | 0.1862 (16) | 0.0105 (6) | 0.0701 (19) | 0.55 |
F13 | 0.7295 (3) | −0.140 (2) | 0.0725 (10) | 0.064 (2) | 0.55 |
F9A | 0.6907 (3) | −0.1311 (19) | 0.2408 (11) | 0.073 (4) | 0.45 |
F10A | 0.6647 (4) | −0.011 (2) | 0.0816 (14) | 0.118 (6) | 0.45 |
F11A | 0.7417 (5) | 0.128 (4) | 0.1932 (19) | 0.103 (7) | 0.45 |
F12A | 0.7178 (3) | 0.267 (2) | 0.0470 (10) | 0.123 (5) | 0.45 |
F13A | 0.7288 (4) | −0.072 (3) | 0.0679 (16) | 0.099 (5) | 0.45 |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0308 (4) | 0.0205 (4) | 0.0274 (4) | 0.000 | 0.0116 (3) | 0.000 |
S2 | 0.0405 (4) | 0.0308 (3) | 0.0316 (3) | 0.0128 (3) | 0.0189 (3) | 0.0087 (2) |
N1 | 0.0332 (10) | 0.0249 (10) | 0.0254 (9) | 0.0026 (8) | 0.0083 (8) | −0.0001 (8) |
C1 | 0.0228 (10) | 0.0251 (11) | 0.0215 (11) | 0.0042 (9) | 0.0036 (8) | 0.0003 (9) |
C2 | 0.0244 (11) | 0.0299 (12) | 0.0313 (12) | 0.0049 (9) | 0.0065 (9) | −0.0025 (10) |
C3 | 0.0338 (12) | 0.0332 (13) | 0.0308 (12) | 0.0104 (10) | 0.0112 (10) | 0.0036 (10) |
C4 | 0.0232 (11) | 0.0289 (12) | 0.0235 (11) | 0.0013 (9) | 0.0008 (9) | 0.0005 (9) |
C5 | 0.0263 (11) | 0.0274 (12) | 0.0273 (11) | 0.0041 (9) | 0.0037 (9) | 0.0026 (10) |
C6 | 0.0284 (12) | 0.0280 (12) | 0.0298 (12) | 0.0004 (10) | 0.0060 (9) | −0.0009 (10) |
C7 | 0.0269 (12) | 0.0351 (13) | 0.0361 (13) | 0.0011 (10) | 0.0084 (10) | −0.0009 (11) |
C8 | 0.0363 (14) | 0.0461 (17) | 0.0465 (16) | 0.0037 (12) | 0.0115 (12) | −0.0092 (14) |
C9 | 0.0382 (17) | 0.065 (2) | 0.064 (2) | 0.0098 (16) | 0.0215 (15) | −0.0073 (19) |
F1 | 0.0452 (8) | 0.0535 (9) | 0.0337 (8) | 0.0231 (7) | 0.0148 (6) | 0.0159 (7) |
F2 | 0.0269 (7) | 0.0560 (10) | 0.0642 (10) | −0.0092 (7) | 0.0126 (7) | −0.0264 (8) |
F3 | 0.0337 (8) | 0.0439 (9) | 0.0597 (10) | −0.0106 (7) | 0.0146 (7) | −0.0245 (8) |
F4 | 0.0621 (10) | 0.0533 (10) | 0.0404 (9) | 0.0282 (8) | 0.0241 (7) | 0.0215 (8) |
F5 | 0.0585 (10) | 0.0325 (8) | 0.0531 (9) | 0.0164 (7) | 0.0279 (8) | 0.0139 (7) |
F6 | 0.0294 (8) | 0.0730 (12) | 0.0569 (10) | −0.0064 (7) | 0.0040 (7) | −0.0358 (9) |
F7 | 0.0266 (8) | 0.0831 (13) | 0.0747 (12) | −0.0072 (8) | 0.0049 (8) | −0.0444 (10) |
F8 | 0.0641 (11) | 0.0496 (10) | 0.0729 (12) | 0.0147 (9) | 0.0373 (9) | 0.0276 (9) |
F9 | 0.067 (4) | 0.079 (7) | 0.051 (3) | 0.046 (4) | 0.016 (3) | 0.027 (3) |
F10 | 0.034 (3) | 0.047 (2) | 0.072 (5) | −0.0019 (16) | 0.008 (3) | −0.036 (2) |
F11 | 0.041 (5) | 0.152 (13) | 0.111 (6) | −0.041 (7) | 0.037 (4) | −0.076 (9) |
F12 | 0.062 (4) | 0.106 (5) | 0.047 (2) | 0.013 (3) | 0.031 (2) | 0.016 (3) |
F13 | 0.053 (3) | 0.058 (6) | 0.083 (4) | 0.021 (3) | 0.028 (3) | −0.031 (3) |
F9A | 0.081 (7) | 0.023 (3) | 0.123 (9) | 0.004 (4) | 0.064 (6) | −0.009 (4) |
F10A | 0.062 (5) | 0.202 (14) | 0.086 (8) | 0.017 (8) | −0.012 (4) | −0.092 (10) |
F11A | 0.033 (4) | 0.102 (8) | 0.177 (16) | 0.005 (5) | 0.025 (7) | −0.046 (8) |
F12A | 0.092 (8) | 0.124 (9) | 0.166 (13) | 0.042 (6) | 0.098 (8) | 0.070 (8) |
F13A | 0.102 (6) | 0.068 (9) | 0.138 (8) | 0.033 (5) | 0.078 (6) | −0.027 (6) |
S1—C1i | 1.741 (2) | C6—F5 | 1.331 (3) |
S1—C1 | 1.741 (2) | C6—F6 | 1.360 (3) |
S2—C1 | 1.747 (2) | C6—C7 | 1.544 (3) |
S2—C2 | 1.816 (2) | C7—F8 | 1.332 (3) |
N1—C1 | 1.300 (3) | C7—F7 | 1.355 (3) |
N1—N1i | 1.396 (4) | C7—C8 | 1.540 (4) |
C2—C3 | 1.529 (3) | C8—F9A | 1.277 (12) |
C2—H2A | 0.9900 | C8—F10 | 1.325 (11) |
C2—H2B | 0.9900 | C8—F9 | 1.374 (9) |
C3—C4 | 1.506 (3) | C8—F10A | 1.383 (16) |
C3—H3A | 0.9900 | C8—C9 | 1.528 (4) |
C3—H3B | 0.9900 | C9—F13A | 1.108 (15) |
C4—F1 | 1.353 (3) | C9—F11 | 1.275 (15) |
C4—F2 | 1.360 (3) | C9—F12A | 1.293 (12) |
C4—C5 | 1.546 (3) | C9—F12 | 1.347 (10) |
C5—F4 | 1.344 (3) | C9—F11A | 1.38 (2) |
C5—F3 | 1.355 (3) | C9—F13 | 1.429 (11) |
C5—C6 | 1.548 (3) | ||
C1i—S1—C1 | 85.62 (15) | F5—C6—C5 | 109.65 (18) |
C1—S2—C2 | 100.09 (10) | F6—C6—C5 | 106.74 (18) |
C1—N1—N1i | 111.92 (12) | C7—C6—C5 | 115.8 (2) |
N1—C1—S1 | 115.27 (16) | F8—C7—F7 | 108.8 (2) |
N1—C1—S2 | 125.32 (16) | F8—C7—C8 | 109.1 (2) |
S1—C1—S2 | 119.41 (13) | F7—C7—C8 | 106.24 (19) |
C3—C2—S2 | 106.43 (16) | F8—C7—C6 | 108.65 (19) |
C3—C2—H2A | 110.4 | F7—C7—C6 | 107.77 (19) |
S2—C2—H2A | 110.4 | C8—C7—C6 | 116.1 (2) |
C3—C2—H2B | 110.4 | F10—C8—F9 | 106.6 (7) |
S2—C2—H2B | 110.4 | F9A—C8—F10A | 112.2 (9) |
H2A—C2—H2B | 108.6 | F9A—C8—C9 | 112.5 (7) |
C4—C3—C2 | 111.9 (2) | F10—C8—C9 | 109.2 (5) |
C4—C3—H3A | 109.2 | F9—C8—C9 | 104.7 (6) |
C2—C3—H3A | 109.2 | F10A—C8—C9 | 99.9 (7) |
C4—C3—H3B | 109.2 | F9A—C8—C7 | 111.7 (6) |
C2—C3—H3B | 109.2 | F10—C8—C7 | 111.7 (4) |
H3A—C3—H3B | 107.9 | F9—C8—C7 | 107.1 (5) |
F1—C4—F2 | 105.92 (19) | F10A—C8—C7 | 102.6 (6) |
F1—C4—C3 | 110.69 (18) | C9—C8—C7 | 116.9 (3) |
F2—C4—C3 | 111.02 (18) | F13A—C9—F12A | 113.0 (12) |
F1—C4—C5 | 107.84 (17) | F11—C9—F12 | 112.0 (10) |
F2—C4—C5 | 108.12 (18) | F13A—C9—F11A | 100.2 (12) |
C3—C4—C5 | 112.95 (19) | F12A—C9—F11A | 102.2 (11) |
F4—C5—F3 | 107.01 (19) | F11—C9—F13 | 111.9 (8) |
F4—C5—C4 | 108.44 (17) | F12—C9—F13 | 103.7 (6) |
F3—C5—C4 | 106.73 (17) | F13A—C9—C8 | 118.0 (10) |
F4—C5—C6 | 108.62 (18) | F11—C9—C8 | 113.8 (7) |
F3—C5—C6 | 108.63 (17) | F12A—C9—C8 | 116.4 (5) |
C4—C5—C6 | 116.98 (19) | F12—C9—C8 | 106.3 (4) |
F5—C6—F6 | 107.6 (2) | F11A—C9—C8 | 103.5 (10) |
F5—C6—C7 | 109.59 (19) | F13—C9—C8 | 108.5 (6) |
F6—C6—C7 | 107.13 (19) |
Symmetry code: (i) −x+1, y, −z+3/2. |
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