Synthesis and crystal structures of 2-bromo-1,3-di­methyl­imidazolium iodides

Short C—Br⋯I inter­actions and C—H⋯I hydrogen bonds are observed in the title compounds.

Abstract

Attempts at direct bromination of 1,3-di­methyl­imidazolium salts were futile. The title compounds, 2-bromo-1,3-di­methyl­imidazolium iodide chloro­form 0.33-solvate, C₅H₈BrN₂ ⁺·I⁻·0.33CHCl₃, 2-bromo-1,3-di­methyl­imidazolium iodide di­chloro­methane hemisolvate, C₅H₈BrN₂ ⁺·I⁻·0.5CH₂Cl₂, and 2-bromo-1,3-di­methyl­imidazolium iodide hemi(diiodide), C₅H₈BrN₂ ⁺·I⁻·0.5I₂, were obtained by methyl­ation of 2-bromo-1-methyl­imidazole. They crystallized as CHCl₃, CH₂Cl₂ or I₂ solvates/adducts. The Br atom acts as a σ-hole to accept short C—Br⋯I inter­actions. C—H⋯I hydrogen bonds are observed in each structure.

Chemical context  

Salts containing 2-bromo-1,3-di­methyl­imidazolium (C₅H₈N₂Br⁺) cations are the objective of this work. They are presumed to be valuable precursors for substitution reactions. This cation, despite its simplicity, has not yet been described. Since brominations in the 1,3-di­meth­oxy­imidazolium series (Laus et al., 2007 ▸) and also bromination of 1-hy­droxy­imidazole-3-oxide (Laus et al., 2012 ▸) gave the respective 2-bromo derivatives, we hoped that in the present case bromination would also yield the desired 2-bromo­imidazolium salts. However, on attempted bromination of 1,3-di­methyl­imidazolium hexa­fluorido­phosphate (Holbrey et al., 2002 ▸), no substitution occurred in the 2-position as indicated by NMR. The absence of P—F vibrations in the infrared spectra suggested the formation of a different anion, which was confirmed by X-ray diffraction. Though direct bromination of the quaternary salt did not yield the desired product, it was discovered that an altered sequence of reaction was successful. Thus, the reaction between the 2-li­thio derivative of 1-methyl­imidazole and an equimolar amount of CBr₄ (Boga et al., 2000 ▸) or Br₂ (El Borai et al., 1981 ▸) gave 2-bromo-1-methyl­imidazole in good yield, followed by methyl­ation using MeI to afford the desired quaternary salt as an iodide.

Now that the elusive title cation has been secured, further modifications are envisioned, giving access to a plethora of new 2-substituted imidazolium derivatives.

Structural commentary  

The 2-bromo-1,3-di­methyl­imidazolium cations and iodide counter-ions crystallize as a CHCl₃ 1/3-solvate (1) (Fig. 1 ▸), a CH₂Cl₂ monosolvate (2) (Fig. 2 ▸) and an I₂ adduct (3) (Fig. 3 ▸). In every case, the cation is almost planar. In the asymmetric unit of 1, there are one and a half ion pairs, which are completed by mirror symmetry; the chloro­form mol­ecule also lies on a crystallographic mirror plane. In 2, there are two cations, two anions and two half-mol­ecules of di­chloro­methane (both completed by crystallographic twofold symmetry) in the asymmetric unit. In 3, the iodine mol­ecule is generated by crystallographic inversion symmetry.

Figure 1.

The mol­ecular structure of the chloro­form solvate 1, showing the atom labels and 50% probability displacement ellipsoids for non-H atoms. [Symmetry code: (i) x, 1 − y, z.]

Figure 2.

The mol­ecular structure of the iodide 2, showing the atom labels and 50% probability displacement ellipsoids for non-H atoms. [Symmetry codes: (i)  − x, y,  − z, (ii)  − x, y,  − z.]

Figure 3.

The mol­ecular structure of the iodide 3, showing the atom labels and 50% probability displacement ellipsoids for non-H atoms. [Symmetry code: (i) 1 − x, 1 − y, −z.]

Supra­molecular features  

Halogen–halogen inter­actions constitute the main supra­molecular features of the three compounds. The cations in 1 are arranged in a tridimensional array of chains by C—H⋯I1 inter­actions. The chloro­form mol­ecule bridges these chains by C—H7⋯Cl1 and C—H9⋯I2 hydrogen bonds (Table 1 ▸). Inter­halogen Br1⋯I2(x, y, −1 + z) [3.544 (1) Å] and Br2⋯I2 [3.546 (2) Å] contacts complete the network (Fig. 4 ▸). The respective C—Br⋯I angles are 173.4 (2) and 173.6 (3)°, indicating an inter­action involving the positive end cap (σ-hole) of the terminal Br atom (Awwadi et al., 2006 ▸; Clark et al., 2007 ▸).

Table 1. Hydrogen-bond geometry (Å, °) for 1 .

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7⋯Cl1i	0.95	2.82	3.623 (7)	142
C8—H8C⋯I1i	0.98	3.02	3.935 (6)	156
C9—H9⋯I2ii	1.00	2.77	3.760 (8)	169
C2—H2⋯I1iii	0.95	3.01	3.932 (6)	165
C3—H3⋯I1iv	0.95	3.12	3.952 (9)	147

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

Figure 4.

The crystal packing of compound 1 viewed along the c axis showing the C—H⋯Cl and C—H⋯I hydrogen bonds (see Table 1 ▸) and Br⋯I short contacts as dashed lines.

This type of inter­action is also identified in the structures of compounds 2 and 3. In the di­chloro­methane solvate 2, almost linear halogen inter­actions Br1⋯I1 [3.483 (1) Å] and Br2⋯I2 [3.411 (1) Å] exhibit C—Br⋯I angles of 173.7 (1) and 176.7 (1)°, respectively (Fig. 5 ▸). The I1 and I2 anions are linked by hydrogen bonds donated by the solvent mol­ecules (Table 2 ▸).

Figure 5.

The crystal packing of compound 2 viewed along the b axis showing the C—H⋯I hydrogen bonds involving the solvent (see Table 2 ▸) and Br⋯I short contacts as dashed lines.

Table 2. Hydrogen-bond geometry (Å, °) for 2 .

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C11—H11A⋯I2i	0.99	2.86	3.834 (2)	169
C12—H12A⋯I1ii	0.99	2.89	3.862 (2)	170

Symmetry codes: (i) ; (ii) .

In 3, a mol­ecular addition compound with iodine (Fig. 6 ▸), inter­actions I1⋯I2 [3.426 (1) Å] and I2—I2 [related by inversion, bond length 2.826 (1) Å] are present. The I1⋯Br(1 + x, y, z) [3.499 (1) Å] inter­action displays a C—Br⋯I angle of 168.0 (2)° (Fig. 6 ▸) and the iodide anion (I1) accepts a hydrogen bond from the methyl group (Table 3 ▸).

Figure 6.

The crystal packing of compound 3 viewed along the a axis showing the C—H⋯I hydrogen bonds (see Table 3 ▸) and Br⋯I and I⋯I short contacts as dashed lines.

Table 3. Hydrogen-bond geometry (Å, °) for 3 .

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5B⋯I1i	0.98	3.03	3.986 (8)	166

Symmetry code: (i) .

Database survey  

A search of the Cambridge Structural Database (Version 5.38; Groom et al., 2016 ▸) for 2-halogeno-1,3-dialkyl or di­aryl­imidazolium salts gave 30 hits. When carbon substituents were allowed in positions 4 and 5, the tally was 34. Of these 64 compounds, there were 11 containing chlorine, 19 bromine and 33 iodine. Closely related imidazolin-2-yl­idene–iodine (Kuhn et al., 1993 ▸) and imidazolin-2-yl­idene–bromine (Kuhn et al., 2004 ▸) coordination compounds have been reported.

Synthesis and crystallization  

Compound 1: A solution of 2-bromo-1-methyl­imidazole (150 µl, 1.54 mmol) in CHCl₃ (1 ml) was carefully layered over a solution of CH₃I (190 µl, 3.07 mmol) in CHCl₃ (2 ml). The mixture was kept at room temperature and protected from light. After 2 h, the formation of colourless crystals of 1 was observed. The product was collected after seven days at 278 K, yielding 252 mg (48%); m.p. 453 K (decomposition). ¹H NMR (300 MHz, DMSO-d ₆): δ 3.81 (s, 6H), 7.90 (s, 2H), 8.31 (s) ppm. ¹³C NMR (75 MHz, DMSO-d ₆): δ 36.8 (2C), 79.3, 123.5, 124.5 (2C) ppm. IR (neat): ν 3066, 2931, 1521, 1240, 1098, 765, 738, 652, 635 cm⁻¹.

Compound 2: A solution of 2-bromo-1-methyl­imidazole (150 µl, 1.54 mmol) in CH₂Cl₂ (1 ml) was carefully layered over a solution of CH₃I (190 µl, 3.07 mmol) in CH₂Cl₂ (2 ml). The mixture was kept at room temperature and protected from light. After 2 h, the formation of colourless crystals of 2 was observed. The product was collected after 18 h, yielding 145 mg (27%); m.p. 452–453 K (decomposition). ¹H NMR (300 MHz, DMSO-d ₆): δ 3.81 (s, 6H), 5.75, 7.90 (s, 2H) ppm. ¹³C NMR (75 MHz, DMSO-d ₆): δ 36.8 (2C), 55.0, 123.3, 124.7 (2C) ppm. IR (neat): ν 3066, 3011, 2944, 1523, 1240, 1101, 779, 728, 696, 635 cm⁻¹.

Compound 3: The I₂ adduct was obtained as a byproduct of 1 and 2 in the form of brown crystals of 3; approximate yield 10%; m.p. 451 K (decomposition). ¹H NMR (300 MHz, DMSO-d ₆): δ 3.81 (s, 6H), 7.89 (d, 2H) ppm IR (neat): ν 3063, 1523, 1226, 739, 634 cm⁻¹.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 4 ▸. All H atoms were poisitioned geometrically (C—H = 0.95–1.0 Å) and treated as riding with U _iso(H) = 1.2–1.5U _eq(C).

Table 4. Experimental details.

	1	2	3
Crystal data
Chemical formula	3C5H8BrN2 +·3I−·CHCl3	2C5H8BrN2 +·2I−·CH2Cl2	C5H8BrN2 +·I−·0.5I2
M r	1028.20	690.79	429.83
Crystal system, space group	Monoclinic, C m	Monoclinic, P2/n	Monoclinic, P21/n
Temperature (K)	173	193	173
a, b, c (Å)	13.9135 (14), 21.9492 (10), 6.4529 (6)	16.0223 (8), 8.5334 (4), 16.2881 (8)	6.0861 (4), 14.4773 (11), 12.0303 (7)
β (°)	128.314 (16)	101.590 (1)	97.812 (5)
V (Å3)	1546.2 (3)	2181.58 (18)	1050.16 (12)
Z	2	4	4
Radiation type	Mo Kα	Mo Kα	Mo Kα
μ (mm−1)	7.18	6.79	9.74
Crystal size (mm)	0.26 × 0.14 × 0.06	0.18 × 0.16 × 0.14	0.36 × 0.10 × 0.08
Data collection
Diffractometer	Gemini-R Ultra	Quest Photon 100	Gemini-R Ultra
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2014 ▸)	Multi-scan (SADABS; Bruker, 2014 ▸)	Analytical
T min, T max	0.427, 1	0.296, 0.433	0.065, 0.446
No. of measured, independent and observed [I > 2σ(I)] reflections	4904, 2522, 2426	62055, 4302, 3952	6287, 1912, 1746
R int	0.026	0.028	0.030
(sin θ/λ)max (Å−1)	0.602	0.617	0.602
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.018, 0.035, 0.95	0.022, 0.063, 1.09	0.036, 0.080, 1.34
No. of reflections	2522	4302	1912
No. of parameters	151	196	93
No. of restraints	2	0	0
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.41, −0.44	1.07, −0.76	0.76, −0.97
Absolute structure	Flack x determined using 961 quotients [(I +)−(I −)]/[(I +)+(I −)] (Parsons et al., 2013 ▸)	–	–
Absolute structure parameter	0.038 (8)	–	–

Computer programs: APEX2 and SAINT (Bruker, 2014 ▸), CrysAlis PRO (Oxford Diffraction, 2014 ▸), SIR2002 (Burla et al., 2003 ▸), SHELXTL (Sheldrick, 2008 ▸), SHELXL2014 and SHELXL2017 (Sheldrick, 2015 ▸), ORTEP-3 for Windows (Farrugia, 2012 ▸) and Mercury (Macrae et al., 2008 ▸).

Supplementary Material

CCDC references: 1826102, 1826101, 1826100

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

supplementary crystallographic information

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Crystal data

3C5H8BrN2+·3I−·CHCl3	F(000) = 956
Mr = 1028.20	Dx = 2.208 Mg m−3
Monoclinic, Cm	Mo Kα radiation, λ = 0.71073 Å
a = 13.9135 (14) Å	Cell parameters from 3263 reflections
b = 21.9492 (10) Å	θ = 3.3–28.4°
c = 6.4529 (6) Å	µ = 7.18 mm−1
β = 128.314 (16)°	T = 173 K
V = 1546.2 (3) Å3	Prismatic, colourless
Z = 2	0.26 × 0.14 × 0.06 mm

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Data collection

Gemini-R Ultra diffractometer	2426 reflections with I > 2σ(I)
Radiation source: Enhance (Mo) X-ray Source	Rint = 0.026
ω scans	θmax = 25.3°, θmin = 3.4°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2014)	h = −16→13
Tmin = 0.427, Tmax = 1	k = −22→26
4904 measured reflections	l = −7→7
2522 independent reflections

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Refinement

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.018	w = 1/[σ2(Fo2) + (0.0049P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.035	(Δ/σ)max < 0.001
S = 0.95	Δρmax = 0.41 e Å−3
2522 reflections	Δρmin = −0.43 e Å−3
151 parameters	Absolute structure: Flack x determined using 961 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
2 restraints	Absolute structure parameter: 0.038 (8)

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Special details

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.

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.12194 (6)	0.39565 (3)	−0.07927 (14)	0.03269 (15)
C2	0.0731 (6)	0.2987 (3)	0.3714 (13)	0.0354 (15)
H2	0.100922	0.279634	0.532098	0.042*
C3	−0.0414 (6)	0.2992 (3)	0.1483 (14)	0.0353 (16)
H3	−0.110268	0.280970	0.121251	0.042*
C1	0.0731 (5)	0.3488 (2)	0.0790 (11)	0.0246 (14)
N1	0.1435 (4)	0.3305 (2)	0.3284 (9)	0.0284 (11)
C4	0.2778 (6)	0.3372 (3)	0.5169 (14)	0.0405 (17)
H4A	0.313345	0.325857	0.430407	0.061*
H4B	0.310751	0.310582	0.669397	0.061*
H4C	0.298588	0.379637	0.576266	0.061*
N2	−0.0420 (4)	0.3308 (2)	−0.0364 (10)	0.0283 (12)
C5	−0.1452 (5)	0.3358 (3)	−0.3220 (12)	0.0353 (15)
H5A	−0.144701	0.376365	−0.385102	0.053*
H5B	−0.222661	0.329753	−0.351574	0.053*
H5C	−0.136654	0.304732	−0.418510	0.053*
I1	0.62590 (4)	0.29885 (2)	0.94514 (6)	0.02823 (10)
I2	0.21304 (5)	0.500000	0.65285 (9)	0.02890 (13)
Br2	0.40367 (7)	0.500000	0.46275 (15)	0.0313 (2)
C8	0.4948 (7)	0.6124 (3)	0.2888 (14)	0.0462 (18)
H8A	0.405961	0.618288	0.177487	0.069*
H8B	0.529339	0.639748	0.230124	0.069*
H8C	0.531481	0.621371	0.472955	0.069*
N3	0.5211 (4)	0.5494 (2)	0.2675 (9)	0.0315 (12)
C6	0.4874 (7)	0.500000	0.3242 (15)	0.0269 (19)
C7	0.5758 (6)	0.5305 (3)	0.1602 (12)	0.0399 (16)
H7	0.607822	0.556086	0.097268	0.048*
C9	0.8764 (8)	0.500000	0.0794 (19)	0.038 (2)
H9	0.962304	0.500000	0.247965	0.045*
Cl1	0.8016 (2)	0.43407 (7)	0.0686 (5)	0.0569 (5)
Cl2	0.8806 (3)	0.500000	−0.1852 (6)	0.0636 (8)

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0383 (3)	0.0293 (3)	0.0368 (3)	−0.0004 (3)	0.0265 (3)	0.0013 (3)
C2	0.052 (4)	0.032 (3)	0.033 (4)	0.001 (3)	0.031 (4)	−0.001 (3)
C3	0.046 (4)	0.031 (4)	0.050 (4)	0.002 (3)	0.040 (4)	0.003 (3)
C1	0.029 (3)	0.019 (3)	0.023 (3)	0.003 (3)	0.015 (3)	−0.003 (3)
N1	0.032 (3)	0.025 (3)	0.026 (3)	0.003 (2)	0.017 (2)	−0.003 (2)
C4	0.043 (4)	0.032 (3)	0.038 (4)	0.006 (3)	0.021 (4)	0.002 (3)
N2	0.028 (3)	0.024 (3)	0.035 (3)	0.002 (2)	0.021 (2)	−0.001 (2)
C5	0.022 (3)	0.033 (3)	0.031 (4)	0.003 (3)	0.007 (3)	0.005 (3)
I1	0.03254 (19)	0.02663 (18)	0.0289 (2)	−0.00359 (18)	0.02071 (17)	0.00012 (18)
I2	0.0286 (3)	0.0344 (3)	0.0280 (3)	0.000	0.0196 (3)	0.000
Br2	0.0373 (5)	0.0385 (5)	0.0292 (5)	0.000	0.0262 (4)	0.000
C8	0.059 (5)	0.044 (4)	0.052 (5)	−0.021 (3)	0.043 (4)	−0.015 (3)
N3	0.028 (3)	0.045 (3)	0.023 (3)	−0.011 (2)	0.016 (2)	−0.005 (2)
C6	0.021 (4)	0.044 (5)	0.018 (4)	0.000	0.013 (4)	0.000
C7	0.031 (3)	0.064 (4)	0.031 (4)	−0.008 (3)	0.022 (3)	−0.004 (3)
C9	0.034 (5)	0.031 (5)	0.053 (6)	0.000	0.030 (5)	0.000
Cl1	0.0748 (12)	0.0285 (7)	0.1059 (15)	0.0015 (10)	0.0751 (12)	0.0040 (11)
Cl2	0.102 (2)	0.0363 (14)	0.097 (2)	0.000	0.084 (2)	0.000

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Geometric parameters (Å, º)

Br1—C1	1.850 (6)	C5—H5C	0.9800
C2—C3	1.329 (9)	Br2—C6	1.857 (8)
C2—N1	1.364 (8)	C8—N3	1.457 (8)
C2—H2	0.9500	C8—H8A	0.9800
C3—N2	1.374 (8)	C8—H8B	0.9800
C3—H3	0.9500	C8—H8C	0.9800
C1—N1	1.325 (7)	N3—C6	1.321 (6)
C1—N2	1.340 (7)	N3—C7	1.372 (7)
N1—C4	1.475 (8)	C7—C7i	1.340 (13)
C4—H4A	0.9800	C7—H7	0.9500
C4—H4B	0.9800	C9—Cl2	1.744 (9)
C4—H4C	0.9800	C9—Cl1i	1.759 (5)
N2—C5	1.480 (8)	C9—Cl1	1.759 (5)
C5—H5A	0.9800	C9—H9	1.0000
C5—H5B	0.9800
C3—C2—N1	107.7 (6)	N2—C5—H5C	109.5
C3—C2—H2	126.1	H5A—C5—H5C	109.5
N1—C2—H2	126.1	H5B—C5—H5C	109.5
C2—C3—N2	107.6 (6)	N3—C8—H8A	109.5
C2—C3—H3	126.2	N3—C8—H8B	109.5
N2—C3—H3	126.2	H8A—C8—H8B	109.5
N1—C1—N2	108.3 (5)	N3—C8—H8C	109.5
N1—C1—Br1	126.2 (4)	H8A—C8—H8C	109.5
N2—C1—Br1	125.3 (4)	H8B—C8—H8C	109.5
C1—N1—C2	108.6 (5)	C6—N3—C7	107.1 (5)
C1—N1—C4	125.2 (5)	C6—N3—C8	126.8 (5)
C2—N1—C4	125.8 (5)	C7—N3—C8	125.8 (5)
N1—C4—H4A	109.5	N3i—C6—N3	110.5 (7)
N1—C4—H4B	109.5	N3i—C6—Br2	124.8 (4)
H4A—C4—H4B	109.5	N3—C6—Br2	124.8 (4)
N1—C4—H4C	109.5	C7i—C7—N3	107.6 (4)
H4A—C4—H4C	109.5	C7i—C7—H7	126.2
H4B—C4—H4C	109.5	N3—C7—H7	126.2
C1—N2—C3	107.7 (5)	Cl2—C9—Cl1i	109.8 (4)
C1—N2—C5	125.0 (5)	Cl2—C9—Cl1	109.8 (4)
C3—N2—C5	126.6 (5)	Cl1i—C9—Cl1	110.8 (5)
N2—C5—H5A	109.5	Cl2—C9—H9	108.8
N2—C5—H5B	109.5	Cl1i—C9—H9	108.8
H5A—C5—H5B	109.5	Cl1—C9—H9	108.8
N1—C2—C3—N2	0.8 (7)	Br1—C1—N2—C5	11.5 (8)
N2—C1—N1—C2	1.8 (6)	C2—C3—N2—C1	0.3 (7)
Br1—C1—N1—C2	178.1 (4)	C2—C3—N2—C5	171.0 (5)
N2—C1—N1—C4	175.1 (5)	C7—N3—C6—N3i	2.1 (8)
Br1—C1—N1—C4	−8.6 (8)	C8—N3—C6—N3i	176.4 (4)
C3—C2—N1—C1	−1.6 (7)	C7—N3—C6—Br2	−177.6 (5)
C3—C2—N1—C4	−174.9 (6)	C8—N3—C6—Br2	−3.3 (10)
N1—C1—N2—C3	−1.3 (6)	C6—N3—C7—C7i	−1.3 (5)
Br1—C1—N2—C3	−177.6 (4)	C8—N3—C7—C7i	−175.7 (5)
N1—C1—N2—C5	−172.2 (5)

Symmetry code: (i) x, −y+1, z.

2-Bromo-1,3-dimethylimidazolium iodide chloroform 0.33-solvate (1). Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7···Cl1i	0.95	2.82	3.623 (7)	142
C8—H8C···I1i	0.98	3.02	3.935 (6)	156
C9—H9···I2ii	1.00	2.77	3.760 (8)	169
C2—H2···I1iii	0.95	3.01	3.932 (6)	165
C3—H3···I1iv	0.95	3.12	3.952 (9)	147

Symmetry codes: (i) x, −y+1, z; (ii) x+1, y, z; (iii) x−1/2, −y+1/2, z; (iv) x−1, y, z−1.

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Crystal data

2C5H8BrN2+·2I−·CH2Cl2	F(000) = 1288
Mr = 690.79	Dx = 2.103 Mg m−3
Monoclinic, P2/n	Mo Kα radiation, λ = 0.71073 Å
a = 16.0223 (8) Å	Cell parameters from 9539 reflections
b = 8.5334 (4) Å	θ = 2.5–26.8°
c = 16.2881 (8) Å	µ = 6.79 mm−1
β = 101.590 (1)°	T = 193 K
V = 2181.58 (18) Å3	Prism, colourless
Z = 4	0.18 × 0.16 × 0.14 mm

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Data collection

Quest Photon 100 diffractometer	4302 independent reflections
Radiation source: Incoatec Microfocus	3952 reflections with I > 2σ(I)
Multi layered optics monochromator	Rint = 0.028
Detector resolution: 10.4 pixels mm-1	θmax = 26.0°, θmin = 2.4°
φ and ω scans	h = −19→19
Absorption correction: multi-scan (SADABS; Bruker, 2014)	k = −10→10
Tmin = 0.296, Tmax = 0.433	l = −20→20
62055 measured reflections

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Refinement

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.022	w = 1/[σ2(Fo2) + (0.0332P)2 + 2.6592P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.063	(Δ/σ)max = 0.001
S = 1.09	Δρmax = 1.07 e Å−3
4302 reflections	Δρmin = −0.76 e Å−3
196 parameters	Extinction correction: SHELXL2014 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraints	Extinction coefficient: 0.00234 (11)

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Special details

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.

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
I1	0.67871 (2)	0.51565 (2)	0.93259 (2)	0.03524 (8)
I2	0.43487 (2)	1.00139 (2)	0.67926 (2)	0.03507 (8)
Br1	0.58435 (2)	0.60778 (4)	0.72654 (2)	0.04235 (10)
Br2	0.23431 (2)	0.90371 (4)	0.57720 (2)	0.03775 (10)
N1	0.44318 (17)	0.5987 (3)	0.58815 (16)	0.0365 (6)
N2	0.54830 (15)	0.7333 (3)	0.55936 (15)	0.0345 (5)
N3	0.06441 (15)	0.7732 (3)	0.54179 (15)	0.0344 (5)
N4	0.09163 (16)	0.9098 (3)	0.43839 (16)	0.0347 (5)
C1	0.52208 (19)	0.6502 (4)	0.61831 (18)	0.0347 (6)
C2	0.4178 (2)	0.6538 (4)	0.50716 (19)	0.0387 (7)
H2	0.3644	0.6356	0.4708	0.046*
C3	0.4831 (2)	0.7381 (4)	0.48965 (19)	0.0389 (7)
H3	0.4841	0.7913	0.4386	0.047*
C4	0.3892 (3)	0.5077 (5)	0.6337 (3)	0.0550 (10)
H4A	0.4211	0.4167	0.6602	0.083*
H4B	0.3382	0.4720	0.5945	0.083*
H4C	0.3724	0.5737	0.6769	0.083*
C5	0.6292 (2)	0.8180 (4)	0.5680 (2)	0.0494 (8)
H5A	0.6345	0.8927	0.6145	0.074*
H5B	0.6305	0.8747	0.5160	0.074*
H5C	0.6765	0.7433	0.5793	0.074*
C6	0.12335 (18)	0.8585 (3)	0.51581 (19)	0.0334 (6)
C7	−0.00661 (19)	0.7668 (4)	0.4784 (2)	0.0383 (7)
H7	−0.0580	0.7122	0.4797	0.046*
C8	0.01002 (19)	0.8519 (4)	0.4140 (2)	0.0387 (7)
H8	−0.0274	0.8689	0.3617	0.046*
C9	0.0746 (2)	0.6917 (5)	0.6219 (2)	0.0503 (8)
H9A	0.1254	0.6251	0.6298	0.075*
H9B	0.0243	0.6266	0.6224	0.075*
H9C	0.0809	0.7686	0.6674	0.075*
C10	0.1357 (3)	1.0097 (5)	0.3880 (3)	0.0530 (10)
H10A	0.1510	1.1091	0.4172	0.080*
H10B	0.0982	1.0301	0.3336	0.080*
H10C	0.1875	0.9569	0.3792	0.080*
C11	0.2500	0.2120 (5)	0.7500	0.0409 (10)
H11A	0.2931	0.1437	0.7324	0.049*	0.5
H11B	0.2069	0.1436	0.7676	0.049*	0.5
Cl1	0.29912 (8)	0.32404 (14)	0.83510 (8)	0.0829 (4)
C12	0.2500	0.7005 (5)	0.2500	0.0416 (10)
H12A	0.2689	0.6322	0.2081	0.050*	0.5
H12B	0.2311	0.6322	0.2919	0.050*	0.5
Cl2	0.16400 (7)	0.81502 (12)	0.20000 (7)	0.0695 (3)

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
I1	0.03410 (12)	0.03872 (13)	0.03155 (12)	0.00227 (8)	0.00338 (9)	0.00373 (7)
I2	0.03022 (12)	0.04024 (13)	0.03290 (12)	0.00221 (7)	0.00191 (8)	−0.00410 (7)
Br1	0.04481 (19)	0.04589 (19)	0.03212 (17)	0.01593 (14)	−0.00236 (13)	0.00018 (13)
Br2	0.03094 (16)	0.04058 (18)	0.03833 (17)	−0.00138 (12)	−0.00111 (12)	−0.01062 (12)
N1	0.0399 (14)	0.0358 (14)	0.0331 (13)	0.0018 (11)	0.0057 (11)	−0.0024 (10)
N2	0.0315 (12)	0.0374 (13)	0.0331 (13)	0.0056 (10)	0.0025 (10)	−0.0051 (11)
N3	0.0320 (13)	0.0379 (13)	0.0326 (13)	0.0021 (10)	0.0050 (10)	−0.0042 (11)
N4	0.0326 (13)	0.0356 (13)	0.0349 (13)	0.0003 (10)	0.0046 (10)	−0.0052 (10)
C1	0.0382 (16)	0.0325 (15)	0.0317 (15)	0.0085 (12)	0.0032 (12)	−0.0038 (12)
C2	0.0384 (16)	0.0429 (17)	0.0315 (15)	0.0033 (14)	−0.0004 (12)	−0.0052 (13)
C3	0.0413 (17)	0.0454 (18)	0.0282 (15)	0.0076 (14)	0.0026 (12)	−0.0018 (13)
C4	0.058 (2)	0.057 (2)	0.051 (2)	−0.0060 (17)	0.0125 (19)	0.0077 (17)
C5	0.0364 (17)	0.054 (2)	0.055 (2)	−0.0011 (15)	0.0048 (15)	−0.0014 (17)
C6	0.0317 (14)	0.0315 (14)	0.0356 (15)	0.0037 (12)	0.0032 (12)	−0.0082 (12)
C7	0.0270 (14)	0.0438 (18)	0.0428 (17)	−0.0011 (12)	0.0039 (12)	−0.0061 (14)
C8	0.0306 (15)	0.0435 (17)	0.0383 (16)	0.0011 (13)	−0.0019 (12)	−0.0042 (14)
C9	0.054 (2)	0.058 (2)	0.0390 (18)	−0.0011 (17)	0.0089 (16)	0.0067 (16)
C10	0.051 (2)	0.061 (2)	0.046 (2)	−0.0109 (17)	0.0077 (17)	0.0060 (16)
C11	0.034 (2)	0.042 (2)	0.046 (3)	0.000	0.0059 (19)	0.000
Cl1	0.0724 (7)	0.0690 (7)	0.0889 (8)	0.0138 (6)	−0.0277 (6)	−0.0346 (6)
C12	0.044 (2)	0.040 (2)	0.037 (2)	0.000	−0.0023 (19)	0.000
Cl2	0.0684 (6)	0.0583 (6)	0.0657 (6)	0.0183 (5)	−0.0249 (5)	−0.0070 (5)

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Geometric parameters (Å, º)

Br1—C1	1.878 (3)	C4—H4C	0.9800
Br2—C6	1.896 (3)	C5—H5A	0.9800
N1—C1	1.335 (4)	C5—H5B	0.9800
N1—C2	1.382 (4)	C5—H5C	0.9800
N1—C4	1.469 (5)	C7—C8	1.345 (5)
N2—C1	1.328 (4)	C7—H7	0.9500
N2—C3	1.380 (4)	C8—H8	0.9500
N2—C5	1.465 (4)	C9—H9A	0.9800
N3—C6	1.327 (4)	C9—H9B	0.9800
N3—C7	1.376 (4)	C9—H9C	0.9800
N3—C9	1.459 (4)	C10—H10A	0.9800
N4—C6	1.335 (4)	C10—H10B	0.9800
N4—C8	1.380 (4)	C10—H10C	0.9800
N4—C10	1.460 (4)	C11—Cl1	1.737 (3)
C2—C3	1.347 (5)	C11—H11A	0.9900
C2—H2	0.9500	C11—H11B	0.9900
C3—H3	0.9500	C12—Cl2	1.751 (3)
C4—H4A	0.9800	C12—H12A	0.9900
C4—H4B	0.9800	C12—H12B	0.9900
C1—N1—C2	108.3 (3)	N3—C6—N4	108.7 (3)
C1—N1—C4	126.7 (3)	N3—C6—Br2	126.5 (2)
C2—N1—C4	124.8 (3)	N4—C6—Br2	124.7 (2)
C1—N2—C3	108.3 (3)	C8—C7—N3	107.5 (3)
C1—N2—C5	126.6 (3)	C8—C7—H7	126.3
C3—N2—C5	124.9 (3)	N3—C7—H7	126.3
C6—N3—C7	108.5 (3)	C7—C8—N4	107.1 (3)
C6—N3—C9	126.0 (3)	C7—C8—H8	126.4
C7—N3—C9	125.4 (3)	N4—C8—H8	126.4
C6—N4—C8	108.2 (3)	N3—C9—H9A	109.5
C6—N4—C10	126.0 (3)	N3—C9—H9B	109.5
C8—N4—C10	125.8 (3)	H9A—C9—H9B	109.5
N2—C1—N1	108.9 (3)	N3—C9—H9C	109.5
N2—C1—Br1	126.6 (2)	H9A—C9—H9C	109.5
N1—C1—Br1	124.5 (2)	H9B—C9—H9C	109.5
C3—C2—N1	106.9 (3)	N4—C10—H10A	109.5
C3—C2—H2	126.5	N4—C10—H10B	109.5
N1—C2—H2	126.5	H10A—C10—H10B	109.5
C2—C3—N2	107.6 (3)	N4—C10—H10C	109.5
C2—C3—H3	126.2	H10A—C10—H10C	109.5
N2—C3—H3	126.2	H10B—C10—H10C	109.5
N1—C4—H4A	109.5	Cl1i—C11—Cl1	113.2 (3)
N1—C4—H4B	109.5	Cl1i—C11—H11A	108.9
H4A—C4—H4B	109.5	Cl1—C11—H11A	108.9
N1—C4—H4C	109.5	Cl1i—C11—H11B	108.9
H4A—C4—H4C	109.5	Cl1—C11—H11B	108.9
H4B—C4—H4C	109.5	H11A—C11—H11B	107.7
N2—C5—H5A	109.5	Cl2—C12—Cl2ii	112.1 (3)
N2—C5—H5B	109.5	Cl2—C12—H12A	109.2
H5A—C5—H5B	109.5	Cl2ii—C12—H12A	109.2
N2—C5—H5C	109.5	Cl2—C12—H12B	109.2
H5A—C5—H5C	109.5	Cl2ii—C12—H12B	109.2
H5B—C5—H5C	109.5	H12A—C12—H12B	107.9
C3—N2—C1—N1	1.4 (3)	C7—N3—C6—N4	1.4 (3)
C5—N2—C1—N1	176.4 (3)	C9—N3—C6—N4	177.9 (3)
C3—N2—C1—Br1	−179.2 (2)	C7—N3—C6—Br2	−179.2 (2)
C5—N2—C1—Br1	−4.3 (4)	C9—N3—C6—Br2	−2.6 (4)
C2—N1—C1—N2	−1.1 (3)	C8—N4—C6—N3	−1.2 (3)
C4—N1—C1—N2	−177.4 (3)	C10—N4—C6—N3	178.9 (3)
C2—N1—C1—Br1	179.5 (2)	C8—N4—C6—Br2	179.3 (2)
C4—N1—C1—Br1	3.2 (4)	C10—N4—C6—Br2	−0.5 (4)
C1—N1—C2—C3	0.3 (3)	C6—N3—C7—C8	−1.0 (3)
C4—N1—C2—C3	176.7 (3)	C9—N3—C7—C8	−177.5 (3)
N1—C2—C3—N2	0.5 (3)	N3—C7—C8—N4	0.2 (4)
C1—N2—C3—C2	−1.2 (3)	C6—N4—C8—C7	0.6 (3)
C5—N2—C3—C2	−176.2 (3)	C10—N4—C8—C7	−179.6 (3)

Symmetry codes: (i) −x+1/2, y, −z+3/2; (ii) −x+1/2, y, −z+1/2.

2-Bromo-1,3-dimethylimidazolium iodide dichloromethane hemisolvate (2). Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11A···I2iii	0.99	2.86	3.834 (2)	169
C12—H12A···I1iv	0.99	2.89	3.862 (2)	170

Symmetry codes: (iii) x, y−1, z; (iv) −x+1, −y+1, −z+1.

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Crystal data

C5H8BrN2+·I−·0.5I2	F(000) = 772
Mr = 429.83	Dx = 2.719 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.0861 (4) Å	Cell parameters from 3142 reflections
b = 14.4773 (11) Å	θ = 3.3–27.6°
c = 12.0303 (7) Å	µ = 9.74 mm−1
β = 97.812 (5)°	T = 173 K
V = 1050.16 (12) Å3	Lath shaped, red-brown
Z = 4	0.36 × 0.10 × 0.08 mm

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Data collection

Gemini-R Ultra diffractometer	1746 reflections with I > 2σ(I)
ω scans	Rint = 0.030
Absorption correction: analytical	θmax = 25.4°, θmin = 3.3°
Tmin = 0.065, Tmax = 0.446	h = −6→7
6287 measured reflections	k = −17→13
1912 independent reflections	l = −14→11

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Refinement

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036	H-atom parameters constrained
wR(F2) = 0.080	w = 1/[σ2(Fo2) + (0.0102P)2 + 8.6812P] where P = (Fo2 + 2Fc2)/3
S = 1.34	(Δ/σ)max < 0.001
1912 reflections	Δρmax = 0.76 e Å−3
93 parameters	Δρmin = −0.97 e Å−3

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Special details

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. 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.

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I1	0.59338 (9)	0.17085 (4)	0.05590 (4)	0.02835 (16)
I2	0.51595 (9)	0.40299 (5)	0.01140 (5)	0.03726 (18)
Br	0.04393 (13)	0.28681 (6)	0.20566 (7)	0.0274 (2)
N2	0.4459 (11)	0.3501 (5)	0.3339 (5)	0.0246 (15)
N1	0.2322 (11)	0.4618 (5)	0.2630 (5)	0.0269 (15)
C1	0.2538 (13)	0.3703 (6)	0.2721 (6)	0.0236 (17)
C4	0.0471 (14)	0.5121 (6)	0.1973 (7)	0.034 (2)
H4A	0.076771	0.518793	0.119610	0.051*
H4B	0.032629	0.573356	0.230131	0.051*
H4C	−0.090958	0.477458	0.198377	0.051*
C3	0.5500 (14)	0.4327 (6)	0.3649 (7)	0.031 (2)
H3	0.690601	0.439536	0.409197	0.037*
C5	0.5298 (14)	0.2578 (6)	0.3667 (7)	0.0293 (19)
H5A	0.422473	0.225817	0.406887	0.044*
H5B	0.671533	0.263396	0.415747	0.044*
H5C	0.551338	0.222595	0.299519	0.044*
C2	0.4191 (15)	0.5011 (6)	0.3217 (7)	0.032 (2)
H2	0.449093	0.565310	0.329958	0.039*

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
I1	0.0248 (3)	0.0341 (3)	0.0254 (3)	−0.0032 (2)	0.0007 (2)	0.0003 (2)
I2	0.0282 (3)	0.0522 (4)	0.0320 (3)	−0.0097 (3)	0.0062 (2)	−0.0096 (3)
Br	0.0267 (4)	0.0248 (5)	0.0306 (4)	−0.0047 (3)	0.0028 (3)	−0.0036 (3)
N2	0.025 (3)	0.030 (4)	0.020 (3)	−0.005 (3)	0.005 (3)	−0.003 (3)
N1	0.030 (4)	0.024 (4)	0.026 (4)	0.001 (3)	0.002 (3)	−0.006 (3)
C1	0.031 (4)	0.021 (4)	0.021 (4)	−0.005 (4)	0.011 (3)	−0.003 (3)
C4	0.035 (5)	0.033 (5)	0.033 (5)	0.008 (4)	−0.003 (4)	0.007 (4)
C3	0.024 (4)	0.034 (5)	0.034 (5)	−0.013 (4)	0.002 (3)	−0.003 (4)
C5	0.029 (4)	0.023 (5)	0.036 (5)	0.002 (4)	0.003 (4)	0.001 (3)
C2	0.041 (5)	0.023 (5)	0.031 (5)	−0.008 (4)	0.002 (4)	−0.003 (4)

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Geometric parameters (Å, º)

I2—I2i	2.8265 (14)	C4—H4B	0.9800
Br—C1	1.858 (8)	C4—H4C	0.9800
N2—C1	1.330 (10)	C3—C2	1.331 (12)
N2—C3	1.380 (11)	C3—H3	0.9500
N2—C5	1.465 (11)	C5—H5A	0.9800
N1—C1	1.335 (11)	C5—H5B	0.9800
N1—C2	1.377 (11)	C5—H5C	0.9800
N1—C4	1.477 (10)	C2—H2	0.9500
C4—H4A	0.9800
C1—N2—C3	107.3 (7)	H4B—C4—H4C	109.5
C1—N2—C5	126.7 (7)	C2—C3—N2	108.1 (7)
C3—N2—C5	125.9 (7)	C2—C3—H3	125.9
C1—N1—C2	107.6 (7)	N2—C3—H3	125.9
C1—N1—C4	126.3 (7)	N2—C5—H5A	109.5
C2—N1—C4	126.0 (7)	N2—C5—H5B	109.5
N2—C1—N1	109.4 (7)	H5A—C5—H5B	109.5
N2—C1—Br	126.8 (6)	N2—C5—H5C	109.5
N1—C1—Br	123.8 (6)	H5A—C5—H5C	109.5
N1—C4—H4A	109.5	H5B—C5—H5C	109.5
N1—C4—H4B	109.5	C3—C2—N1	107.6 (8)
H4A—C4—H4B	109.5	C3—C2—H2	126.2
N1—C4—H4C	109.5	N1—C2—H2	126.2
H4A—C4—H4C	109.5
C3—N2—C1—N1	−0.1 (8)	C4—N1—C1—Br	−2.2 (11)
C5—N2—C1—N1	178.0 (7)	C1—N2—C3—C2	0.2 (9)
C3—N2—C1—Br	179.2 (6)	C5—N2—C3—C2	−177.9 (7)
C5—N2—C1—Br	−2.7 (11)	N2—C3—C2—N1	−0.2 (10)
C2—N1—C1—N2	0.0 (9)	C1—N1—C2—C3	0.2 (9)
C4—N1—C1—N2	177.1 (7)	C4—N1—C2—C3	−177.0 (8)
C2—N1—C1—Br	−179.4 (6)

Symmetry code: (i) −x+1, −y+1, −z.

2-Bromo-1,3-dimethylimidazolium iodide hemi(diiodide) (3). Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5B···I1ii	0.98	3.03	3.986 (8)	166

Symmetry code: (ii) x+1/2, −y+1/2, z+1/2.