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

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ISSN: 2414-3146

1-Vinyl-4-imidazoline-2-thione

aUniversity of Innsbruck, Faculty of Chemistry and Pharmacy, Innrain 80-82, 6020 Innsbruck, Austria
*Correspondence e-mail: herwig.schottenberger@uibk.ac.at

Edited by P. McArdle, National University of Ireland, Ireland (Received 12 July 2017; accepted 22 August 2017; online 25 August 2017)

The title compound, C5H6N2S, was obtained by deprotonation of 1-vinyl­imidazole and subsequent reaction with elemental sulfur. In the crystal, the molecules are linked by N—H⋯S and C—H⋯S hydrogen bonds, and arranged in layers parallel to the ab plane.

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

Structure description

Imidazoline-2-thio­nes (Laus et al., 2013[Laus, G., Kahlenberg, V., Wurst, K., Müller, T., Kopacka, H. & Schottenberger, H. (2013). Z. Naturforsch. Teil B, 68, 1239-1252.]) are versatile and easy-to-synthesize building blocks. The title compound is one of the small mol­ecules whose structure, surprisingly, has not yet been described. Not only is the mol­ecule itself inter­esting, it also allows further derivatization at the S and N atoms (Hummel et al., 2017[Hummel, M., Markiewicz, M., Stolte, S., Noisternig, M., Braun, D. E., Gelbrich, T., Griesser, U. J., Partl, G., Naier, B., Wurst, K., Krüger, B., Kopacka, H., Laus, G., Huppertz, H. & Schottenberger, H. (2017). Green Chem. 19, 3225-3237.]; Oberparleiter et al., 2016[Oberparleiter, S., Laus, G., Wurst, K. & Schottenberger, H. (2016). IUCrData, 1, x161499.]), and gives access to a plethora of functionalized imidazolium salts. The primary alkyl­ation takes place at the S atom; the resulting salt can then be deprotonated to yield a neutral 2-alkyl­sulfanyl-1-vinyl­imidazole, which can then be transformed into a quaternary salt. In addition, the vinyl substituent renders the mol­ecule polymerizable and thus permits a path to imidazole-based polymers (Anderson & Long, 2010[Anderson, E. B. & Long, T. E. (2010). Polymer, 51, 2447-2454.]; Nakabayashi & Mori, 2013[Nakabayashi, K. & Mori, H. (2013). Eur. Polym. J. 49, 2808-2838.]).

The synthesis of the title compound involves deprotonation of 1-vinyl­imidazole and subsequent reaction with elemental sulfur. Strong bases, such as iso­propyl­magnesium chloride or hexyl­lithium, are required. Other reaction conditions, such as sulfur in KOH/DMSO (Yuan et al., 2010[Yuan, Y., Thom, I., Kim, S. H., Chen, D., Beyer, A., Bonnamour, J., Zuidema, E., Chang, S. & Bolm, C. (2010). Adv. Synth. Catal. 352, 2892-2898.]), K2CO3/MeOH (Ansell et al., 1970[Ansell, G. B., Forkey, D. M. & Moore, D. W. (1970). Chem. Commun. pp. 56-57.]) or Et3N/pyridine (Becker et al., 1973[Becker, H. G. O., Nagel, D. & Timpe, H. J. (1973). J. Prakt. Chem. 315, 97-105.]), did not yield the desired product.

The C=S bond length of 1.688 (1) Å is in agreement with the accepted value of 1.68±0.02 Å for imidazoline-2-thio­nes (Laus et al., 2013[Laus, G., Kahlenberg, V., Wurst, K., Müller, T., Kopacka, H. & Schottenberger, H. (2013). Z. Naturforsch. Teil B, 68, 1239-1252.]), ruling out the possibility of a thiol tautomer. The mol­ecular structure is depicted in Fig. 1[link]. The imidazoline-2-thione mol­ecules are linked by N—H⋯S and C—H⋯S hydrogen bonds (Table 1[link]) to form layers, which are arranged parallel to the ab plane (Fig. 2[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2N⋯S1i 0.86 (1) 2.54 (1) 3.378 (1) 167 (1)
C2—H2⋯S1ii 0.95 2.82 3.728 (1) 160
Symmetry codes: (i) [-x, y, -z+{\script{1\over 2}}]; (ii) [x+{\script{1\over 2}}, y-{\script{1\over 2}}, z].
[Figure 1]
Figure 1
The mol­ecular structure of the title compound, showing the atom labels and 50% probability displacement ellipsoids for the non-H atoms.
[Figure 2]
Figure 2
The unit cell of the title compound, viewed in the direction of (a) the a axis, (b) the b axis and (c) the c axis.

Related structures, such as 3-(1H,1H,2H,2H-perfluoro­oct­yl)-1-vinyl­imidazoline-2-thione (Partl, Laus, Gelbrich et al., 2017[Partl, G., Laus, G., Gelbrich, T., Wurst, K., Huppertz, H. & Schottenberger, H. (2017). IUCrData, 2, x170648.]) and 3,3′-(hexane-1,6-di­yl)bis­(1-vinyl­imidazoline-2-thione) (Partl, Laus, Kahlenberg et al., 2017[Partl, G., Laus, G., Kahlenberg, V., Huppertz, H. & Schottenberger, H. (2017). IUCrData, 2, x170599.]), have been reported recently. Polymorphs of the analogous 1-methyl­imidazoline-2-thione (`methimazole') have been described (Lodochnikova et al., 2013[Lodochnikova, O. A., Bodrov, A. V., Saifina, A. F., Nikitina, L. E. & Litvinov, I. A. (2013). J. Struct. Chem. 54, 140-147.]).

Synthesis and crystallization

Method A: iso­propyl­magnesium chloride solution (10 ml, 2 M in Et2O, 20.0 mmol) was added to a solution of 1-vinyl­imidazole (1.52 g, 16.1 mmol) in anhydrous tetra­hydro­furan (THF; 15 ml), and the mixture was stirred for 17 h under an argon atmosphere. Elemental sulfur (573 mg, 17.9 mmol) was added to the clear solution and stirring was continued at room temperature. After 28 h, H2O (20 ml) was added and acidified with HCl (30 ml, 1 M, 30.0 mmol). The mixture was extracted with chloro­form (3 × 40 ml). The combined organic phases were washed with H2O (2 × 60 ml). The solvent was removed under reduced pressure, yielding 1.43 g (70%) of 1-vinyl­imidazoline-2-thione as an off-white solid.

Method B: n-hexyl­lithium (16 ml, 2.3 M in hexa­nes, 36.8 mmol) was added to a cooled (193 K) solution of 1-vinyl­imidazole (3.07 g, 32.6 mmol) in anhydrous THF (40 ml) under an argon atmosphere. The mixture was stirred for 2 h at 195 K and then for 1 h at 263 K. Sulfur (1.1 g, 34.2 mmol) was added and stirring was continued for 68 h. The reaction was quenched with H2O (20 ml) and acidified with HCl (51 ml, 1 M, 51.0 mmol). The THF was removed under reduced pressure, and the residue was extracted with CHCl3 (3 × 100 ml) and with EtOAc (100 ml). The combined organic phases were washed with H2O (100 ml). The solution was treated with activated charcoal, followed by filtration over celite. The solvent was removed under reduced pressure and the product dried overnight at high vacuum, yielding 2.2 g (54%) of 1-vinyl­imidazoline-2-thione as an off-white solid. Single crystals were obtained by slow evaporation of a solution in CHCl3 (m.p. 416–418 K; sublimation above 396 K). The PXRD (Mo Kα radiation) of the bulk material was an excellent match to that calculated from the single-crystal diffraction data (Fig. 3[link]), indicating phase purity.

[Figure 3]
Figure 3
Rietveld fit (Rwp = 0.126, Rexp  = 0.121, Rp = 0.096, goodness-of-fit = 1.04) of the PXRD data with a model calculated from the structural data of the single-crystal structure determination. Black dots indicate raw data, while the red line indicates the calculated model. Tick marks (green) are the 2θ positions for the hkl reflections. The difference curve is shown in blue.

1H NMR (300 MHz, DMSO-d6): δ 12.35 (s, 1H), 7.52 (t, J = 2.1 Hz, 1H), 7.38 (dd, J = 16.1, 9.1 Hz, 1H), 7.04 (t, J = 2.6 Hz, 1H), 5.43 (dd, J = 16.2, 1.3 Hz, 1H), 4.92 (dd, J = 9.1, 1.4 Hz, 1H). 13C NMR (75 MHz, DMSO-d6): δ 161.8, 129.0, 116.3, 113.8, 101.0. IR (neat): ν 3120, 3108, 3006, 1646, 1568, 1462, 1414, 1285, 1267, 1244, 1122, 1090, 1022, 960, 875, 772, 742, 682, 651, 545, 491 cm−1.

Refinement

The H atom at N2 was found and refined isotropically with an N—H bond-length restraint of 0.87 (2) Å. Crystal data, data collection and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C5H6N2S
Mr 126.18
Crystal system, space group Monoclinic, C2/c
Temperature (K) 173
a, b, c (Å) 10.7775 (3), 9.6848 (3), 12.1792 (4)
β (°) 108.139 (1)
V3) 1208.06 (6)
Z 8
Radiation type Mo Kα
μ (mm−1) 0.42
Crystal size (mm) 0.17 × 0.12 × 0.07
 
Data collection
Diffractometer Bruker D8 QUEST PHOTON 100
Absorption correction Multi-scan (SADABS; Bruker, 2014[Bruker (2014). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.864, 0.911
No. of measured, independent and observed [I > 2σ(I)] reflections 16916, 1187, 1114
Rint 0.026
(sin θ/λ)max−1) 0.617
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.065, 1.08
No. of reflections 1187
No. of parameters 78
No. of restraints 1
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.24, −0.22
Computer programs: APEX2 (Bruker, 2014[Bruker (2014). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SAINT (Bruker, 2014[Bruker (2014). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), XT in SHELXTL (Bruker, 2014[Bruker (2014). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), 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, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: XT in SHELXTL (Bruker, 2014); 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).

1-Vinyl-4-imidazoline-2-thione top
Crystal data top
C5H6N2SDx = 1.387 Mg m3
Mr = 126.18Melting point: 418 K
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 10.7775 (3) ÅCell parameters from 9910 reflections
b = 9.6848 (3) Åθ = 2.9–26.4°
c = 12.1792 (4) ŵ = 0.42 mm1
β = 108.139 (1)°T = 173 K
V = 1208.06 (6) Å3Prism, colourless
Z = 80.17 × 0.12 × 0.07 mm
F(000) = 528
Data collection top
Bruker D8 QUEST PHOTON 100
diffractometer
1187 independent reflections
Radiation source: Incoatec Microfocus1114 reflections with I > 2σ(I)
Multi layered optics monochromatorRint = 0.026
Detector resolution: 10.4 pixels mm-1θmax = 26.0°, θmin = 2.9°
φ and ω scansh = 1313
Absorption correction: multi-scan
(SADABS; Bruker, 2014)
k = 1111
Tmin = 0.864, Tmax = 0.911l = 1515
16916 measured reflections
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.024 w = 1/[σ2(Fo2) + (0.0314P)2 + 1.0869P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.065(Δ/σ)max < 0.001
S = 1.08Δρmax = 0.24 e Å3
1187 reflectionsΔρmin = 0.22 e Å3
78 parametersExtinction correction: SHELXL2014 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.0068 (9)
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. Hydrogen atom at N2 were found and refined isotropically with bond restraint (d=87pm).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S10.11344 (3)0.54728 (4)0.42718 (3)0.02539 (14)
N10.31623 (10)0.38500 (11)0.41324 (9)0.0200 (2)
N20.17797 (11)0.43417 (12)0.24678 (9)0.0225 (2)
H2N0.1110 (15)0.4659 (17)0.1942 (13)0.034 (4)*
C10.20309 (12)0.45566 (12)0.36118 (11)0.0192 (3)
C20.35897 (13)0.32017 (14)0.32890 (11)0.0241 (3)
H20.43490.26470.34210.029*
C30.27288 (13)0.35079 (14)0.22622 (11)0.0250 (3)
H30.27620.32090.15290.030*
C40.37875 (13)0.38285 (14)0.53361 (11)0.0262 (3)
H40.33200.41760.58210.031*
C50.49716 (14)0.33608 (16)0.58291 (12)0.0327 (3)
H5A0.54660.30060.53690.039*
H5B0.53350.33760.66470.039*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.01913 (19)0.0318 (2)0.0239 (2)0.00659 (12)0.00469 (13)0.00509 (12)
N10.0173 (5)0.0214 (5)0.0203 (5)0.0030 (4)0.0045 (4)0.0000 (4)
N20.0179 (5)0.0267 (6)0.0197 (5)0.0030 (4)0.0014 (4)0.0020 (4)
C10.0159 (6)0.0192 (6)0.0213 (6)0.0016 (4)0.0042 (5)0.0007 (4)
C20.0215 (6)0.0253 (7)0.0260 (7)0.0045 (5)0.0081 (5)0.0034 (5)
C30.0226 (6)0.0280 (7)0.0244 (7)0.0015 (5)0.0074 (5)0.0055 (5)
C40.0277 (7)0.0303 (7)0.0199 (6)0.0060 (5)0.0066 (5)0.0020 (5)
C50.0319 (8)0.0397 (8)0.0227 (7)0.0104 (6)0.0028 (6)0.0026 (6)
Geometric parameters (Å, º) top
S1—C11.6884 (13)C2—C31.3380 (19)
N1—C11.3695 (16)C2—H20.9500
N1—C21.3986 (16)C3—H30.9500
N1—C41.4102 (16)C4—C51.3104 (19)
N2—C11.3502 (16)C4—H40.9500
N2—C31.3858 (17)C5—H5A0.9500
N2—H2N0.859 (14)C5—H5B0.9500
C1—N1—C2109.49 (10)N1—C2—H2126.4
C1—N1—C4123.85 (11)C2—C3—N2107.24 (11)
C2—N1—C4126.64 (11)C2—C3—H3126.4
C1—N2—C3110.74 (11)N2—C3—H3126.4
C1—N2—H2N124.5 (11)C5—C4—N1124.29 (13)
C3—N2—H2N124.7 (11)C5—C4—H4117.9
N2—C1—N1105.33 (11)N1—C4—H4117.9
N2—C1—S1127.71 (10)C4—C5—H5A120.0
N1—C1—S1126.95 (10)C4—C5—H5B120.0
C3—C2—N1107.21 (11)H5A—C5—H5B120.0
C3—C2—H2126.4
C3—N2—C1—N10.31 (14)C1—N1—C2—C30.01 (15)
C3—N2—C1—S1178.63 (10)C4—N1—C2—C3178.69 (12)
C2—N1—C1—N20.18 (14)N1—C2—C3—N20.19 (15)
C4—N1—C1—N2178.55 (11)C1—N2—C3—C20.32 (15)
C2—N1—C1—S1178.77 (10)C1—N1—C4—C5167.81 (14)
C4—N1—C1—S12.51 (18)C2—N1—C4—C510.7 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2N···S1i0.86 (1)2.54 (1)3.378 (1)167 (1)
C2—H2···S1ii0.952.823.728 (1)160
Symmetry codes: (i) x, y, z+1/2; (ii) x+1/2, y1/2, z.
 

Acknowledgements

We are grateful to Barbara Schmidt for technical assistance.

References

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