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

Partl, G.; Laus, G.; Wurst, K.; Kopacka, H.; Müller, T.; Huppertz, H.; Schottenberger, H.

doi:10.1107/S2414314617001109

organic compounds

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ISSN: 2414-3146

Volume 2| Part 2| February 2017| x170110

https://doi.org/10.1107/S2414314617001109

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

Gabriel Partl,^a Gerhard Laus,^a Klaus Wurst,^a Holger Kopacka,^a Thomas Müller,^a Hubert Huppertz ^a and Herwig Schottenberger ^a ^*

^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.

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 R_F-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) telomer thioether, comparable to the title compound, to sulfonate by aerobic biological oxidation is noteworthy (Harding-Marjanovic et al., 2015 ). A related tridecafluorooctylthiol-derived crystal structure 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 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). 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.

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
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.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₈H₈F₂₆N₂S₃
M_r	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)
V (Å³)	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 )
T_min, T_max	0.844, 0.914
No. of measured, independent and observed [I > 2σ(I)] reflections	26073, 2448, 2213
R_int	0.045
(sin θ/λ)_max (Å⁻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
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.25
Computer programs: APEX2 and SAINT (Bruker, 2012), XT in SHELXTL (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ) and Mercury (Macrae et al., 2008 ).

Structural data

CCDC reference: 1528993

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314617001109/hb4113sup1.cif

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

checkCIF report

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

C₁₈H₈F₂₆N₂S₃	F(000) = 1648
M_r = 842.44	D_x = 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

Data collection top

Bruker D8 QUEST PHOTON 100 diffractometer	2448 independent reflections
Radiation source: Incoatec Microfocus	2213 reflections with I > 2σ(I)
Multi layered optics monochromator	R_int = 0.045
Detector resolution: 10.4 pixels mm^-1	θ_max = 25.0°, θ_min = 3.0°
φ and ω scans	h = −48→48
Absorption correction: multi-scan (SADABS; Bruker, 2012)	k = −6→6
T_min = 0.844, T_max = 0.914	l = −14→13
26073 measured reflections

Refinement top

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(F_o²) + (0.0443P)² + 5.7325P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.099	(Δ/σ)_max = 0.002
S = 1.10	Δρ_max = 0.45 e Å⁻³
2448 reflections	Δρ_min = −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)

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

	x	y	z	U_iso*/U_eq	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

Atomic displacement parameters (Å²) top

	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)

Geometric parameters (Å, º) top

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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