Crystal structure of a methimazole-based ionic liquid.

The structure of 1-methyl-2-(prop-2-en-1-ylsulfan-yl)-1H-imidazol-3-ium bromide, C7H11N2S(+)·Br(-), has monoclinic (P21/c) symmetry. In the crystal, the components are linked by N-H⋯Br and C-H⋯Br hydrogen bonds. The crystal structure of the title compound undeniably proves that methimazole reacts through the thione tautomer, rather than the thiol tautomer in this system.

Related literature

For the biological activity of methimazole, see: Rong et al. (2013 ▸). For its use as a ligand, see: Crossley et al. (2006 ▸). For a discussion of methimazole-based ionic liquids, see: Siriwardana et al. (2008 ▸). For reaction chemistry of methimazole, see: Roy & Mugesh (2005 ▸).

Experimental

Crystal data

C7H11N2S+·Br−

M = 235.15

Monoclinic,

a = 10.8692 (7) Å

b = 7.4103 (5) Å

c = 12.8551 (9) Å

β = 104.006 (7)°

V = 1004.62 (11) Å3

Z = 4

Mo Kα radiation

μ = 4.24 mm−1

T = 180 K

0.6 × 0.32 × 0.25 mm

Data collection

Agilent Xcalibur, Eos diffractometer

Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014 ▸) T min = 0.321, T max = 1.000

7388 measured reflections

1829 independent reflections

1558 reflections with I > 2σ(I)

R int = 0.042

Refinement

R[F 2 > 2σ(F 2)] = 0.030

wR(F 2) = 0.065

S = 1.03

1829 reflections

105 parameters

1 restraint

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.34 e Å−3

Δρmin = −0.38 e Å−3

Data collection: CrysAlis PRO (Agilent, 2014 ▸); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: OLEX2 (Dolomanov et al., 2009 ▸); software used to prepare material for publication: OLEX2 and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S2056989015022136/hg5463sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015022136/hg5463Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989015022136/hg5463Isup3.cml

Click here for additional data file.

. DOI: 10.1107/S2056989015022136/hg5463fig1.tif

A thermal ellipsoid diagram of the structure of the title compound.

Click here for additional data file.

. DOI: 10.1107/S2056989015022136/hg5463fig2.tif

Reaction scheme.

CCDC reference: 1437865

Additional supporting information: crystallographic information; 3D view; checkCIF report

C7H11N2S+·Br−	F(000) = 472
Mr = 235.15	Dx = 1.555 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.8692 (7) Å	Cell parameters from 2203 reflections
b = 7.4103 (5) Å	θ = 3.9–27.0°
c = 12.8551 (9) Å	µ = 4.24 mm−1
β = 104.006 (7)°	T = 180 K
V = 1004.62 (11) Å3	Prism, colourless
Z = 4	0.6 × 0.32 × 0.25 mm

Agilent Xcalibur, Eos diffractometer	1829 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1558 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
Detector resolution: 16.0514 pixels mm-1	θmax = 25.3°, θmin = 3.2°
ω scans	h = −13→13
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	k = −8→8
Tmin = 0.321, Tmax = 1.000	l = −15→15
7388 measured reflections

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.065	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ2(Fo2) + (0.027P)2] where P = (Fo2 + 2Fc2)/3
1829 reflections	(Δ/σ)max = 0.001
105 parameters	Δρmax = 0.34 e Å−3
1 restraint	Δρmin = −0.38 e Å−3

Experimental. CrysAlis Pro (Agilent, 2014) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

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 > 2σ(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.

	x	y	z	Uiso*/Ueq
Br1	0.70880 (3)	0.66161 (4)	0.53045 (2)	0.02621 (12)
N2	0.6562 (2)	0.0414 (3)	0.2392 (2)	0.0273 (6)
N1	0.6302 (2)	0.1226 (3)	0.39296 (18)	0.0233 (6)
C2	0.5297 (3)	0.0739 (4)	0.2258 (3)	0.0316 (8)
H2A	0.4669	0.0623	0.1625	0.038*
C3	0.5134 (3)	0.1262 (4)	0.3221 (3)	0.0285 (7)
H3	0.4371	0.1587	0.3376	0.034*
C1	0.7171 (3)	0.0704 (4)	0.3410 (2)	0.0234 (7)
S1	0.87834 (8)	0.04183 (11)	0.39532 (7)	0.0373 (2)
C4	0.6547 (4)	0.1637 (4)	0.5076 (2)	0.0370 (9)
H4A	0.5756	0.1749	0.5278	0.055*
H4B	0.7009	0.2750	0.5221	0.055*
H4C	0.7037	0.0681	0.5481	0.055*
C6	0.9092 (3)	0.3747 (4)	0.3027 (3)	0.0410 (9)
H6	0.9450	0.3274	0.2498	0.049*
C5	0.9322 (3)	0.2790 (4)	0.4066 (3)	0.0405 (9)
H5A	0.8889	0.3429	0.4532	0.049*
H5B	1.0223	0.2818	0.4401	0.049*
C7	0.8417 (3)	0.5215 (5)	0.2809 (3)	0.0436 (9)
H7A	0.8047	0.5719	0.3323	0.052*
H7B	0.8305	0.5758	0.2141	0.052*
H2	0.689 (3)	0.007 (4)	0.190 (2)	0.049 (11)*

	U11	U22	U33	U12	U13	U23
Br1	0.02573 (18)	0.0284 (2)	0.02529 (19)	−0.00350 (13)	0.00772 (13)	−0.00185 (13)
N2	0.0309 (15)	0.0295 (16)	0.0227 (15)	0.0016 (12)	0.0088 (13)	−0.0005 (12)
N1	0.0304 (15)	0.0165 (13)	0.0238 (14)	−0.0003 (11)	0.0081 (12)	0.0002 (10)
C2	0.0256 (17)	0.030 (2)	0.0354 (19)	−0.0008 (14)	−0.0003 (15)	0.0026 (15)
C3	0.0190 (16)	0.0255 (18)	0.041 (2)	0.0028 (13)	0.0064 (14)	0.0023 (15)
C1	0.0253 (17)	0.0180 (17)	0.0264 (17)	−0.0015 (13)	0.0057 (14)	0.0027 (13)
S1	0.0229 (4)	0.0335 (5)	0.0518 (6)	0.0031 (4)	0.0019 (4)	0.0112 (4)
C4	0.059 (2)	0.028 (2)	0.0254 (18)	−0.0016 (16)	0.0128 (17)	−0.0035 (14)
C6	0.039 (2)	0.045 (2)	0.044 (2)	−0.0026 (17)	0.0186 (18)	0.0108 (18)
C5	0.0249 (18)	0.040 (2)	0.051 (2)	−0.0105 (15)	−0.0023 (16)	0.0134 (17)
C7	0.049 (2)	0.042 (2)	0.037 (2)	0.0000 (18)	0.0056 (18)	0.0126 (17)

N2—C2	1.366 (4)	C4—H4A	0.9600
N2—C1	1.334 (4)	C4—H4B	0.9600
N2—H2	0.836 (17)	C4—H4C	0.9600
N1—C3	1.373 (4)	C6—H6	0.9300
N1—C1	1.338 (3)	C6—C5	1.480 (4)
N1—C4	1.465 (4)	C6—C7	1.304 (4)
C2—H2A	0.9300	C5—H5A	0.9700
C2—C3	1.349 (4)	C5—H5B	0.9700
C3—H3	0.9300	C7—H7A	0.9300
C1—S1	1.736 (3)	C7—H7B	0.9300
S1—C5	1.847 (3)
C2—N2—H2	124 (2)	N1—C4—H4B	109.5
C1—N2—C2	109.9 (3)	N1—C4—H4C	109.5
C1—N2—H2	126 (2)	H4A—C4—H4B	109.5
C3—N1—C4	125.3 (3)	H4A—C4—H4C	109.5
C1—N1—C3	109.0 (2)	H4B—C4—H4C	109.5
C1—N1—C4	125.7 (3)	C5—C6—H6	118.1
N2—C2—H2A	126.7	C7—C6—H6	118.1
C3—C2—N2	106.7 (3)	C7—C6—C5	123.8 (3)
C3—C2—H2A	126.7	S1—C5—H5A	108.8
N1—C3—H3	126.3	S1—C5—H5B	108.8
C2—C3—N1	107.3 (3)	C6—C5—S1	113.8 (2)
C2—C3—H3	126.3	C6—C5—H5A	108.8
N2—C1—N1	107.1 (3)	C6—C5—H5B	108.8
N2—C1—S1	126.0 (2)	H5A—C5—H5B	107.7
N1—C1—S1	126.9 (2)	C6—C7—H7A	120.0
C1—S1—C5	100.68 (14)	C6—C7—H7B	120.0
N1—C4—H4A	109.5	H7A—C7—H7B	120.0
N2—C2—C3—N1	−0.7 (3)	C1—N2—C2—C3	0.7 (4)
N2—C1—S1—C5	104.2 (3)	C1—N1—C3—C2	0.5 (3)
N1—C1—S1—C5	−77.0 (3)	C1—S1—C5—C6	−61.4 (3)
C2—N2—C1—N1	−0.4 (3)	C4—N1—C3—C2	−177.7 (3)
C2—N2—C1—S1	178.7 (2)	C4—N1—C1—N2	178.1 (3)
C3—N1—C1—N2	−0.1 (3)	C4—N1—C1—S1	−0.9 (4)
C3—N1—C1—S1	−179.1 (2)	C7—C6—C5—S1	121.8 (3)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···Br1i	0.84 (3)	2.46 (3)	3.246 (2)	158 (3)
C2—H2A···Br1ii	0.93	2.84	3.723 (4)	159
C3—H3···Br1iii	0.93	2.91	3.757 (3)	152
C4—H4B···Br1	0.96	2.87	3.737 (3)	151
C5—H5B···Br1iv	0.97	2.89	3.814 (3)	161

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯Br1i	0.84 (3)	2.46 (3)	3.246 (2)	158 (3)
C2—H2A⋯Br1ii	0.93	2.84	3.723 (4)	159
C3—H3⋯Br1iii	0.93	2.91	3.757 (3)	152
C4—H4B⋯Br1	0.96	2.87	3.737 (3)	151
C5—H5B⋯Br1iv	0.97	2.89	3.814 (3)	161

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .