4,5-Dibromo-1,2-dimethyl-1H-imidazol-3-ium bromide

Abstract

In the title salt, C₅H₇Br₂N₂ ⁺·Br⁻, the cation and anion are connected by an N—H⋯Br hydrogen bond. In the crystal, there are inter­calated layers parallel to (10-2) in which bromide ions are located between the cations. Weak inter­molecular C—H⋯Br hydrogen bonds are also observed.

Related literature  

For the preparation of the title compound using the Ortoleva–King reaction, see: King (1944 ▶). For applications of C,N-substituted haloimidazole derivatives, see: Reepmeyer et al. (1975 ▶); Zamora et al. (2003 ▶); Schmidt & Schieffer (2003 ▶); Mashkovskii (2005 ▶); Amini et al. (2007 ▶).

Experimental  

Crystal data  

• C₅H₇Br₂N₂ ⁺·Br⁻

• M _r = 334.86

• Monoclinic,

• a = 5.5938 (3) Å

• b = 11.2522 (6) Å

• c = 14.4864 (9) Å

• β = 104.571 (3)°

• V = 882.48 (9) ų

• Z = 4

• Mo Kα radiation

• μ = 13.64 mm⁻¹

• T = 150 K

• 0.31 × 0.22 × 0.17 mm

Data collection  

• Bruker APEXII diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2002 ▶) T _min = 0.058, T _max = 0.098

• 7565 measured reflections

• 2032 independent reflections

• 1747 reflections with I > 2σ(I)

• R _int = 0.050

Refinement  

• R[F ² > 2σ(F ²)] = 0.027

• wR(F ²) = 0.060

• S = 1.03

• 2032 reflections

• 94 parameters

• H-atom parameters constrained

• Δρ_max = 0.63 e Å⁻³

• Δρ_min = −0.86 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SIR2002 (Burla et al., 2005 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and DIAMOND (Brandenburg & Berndt, 2001 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Supplementary material file. DOI: 10.1107/S1600536812015310/lh5448Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N5—H5⋯Br3i	0.88	2.35	3.216 (3)	168
C6—H6A⋯Br2ii	0.96	2.90	3.796 (3)	156

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

Imidazole is an important synthon for the synthesis of diverse derivatives and various condensed heterocycles. The C,N-substituted haloimidazole derivatives have shown a high pharmacological activity (Zamora et al., 2003; Schmidt et al., 2003) and some have found practical use in medicine (Mashkovskii, 2005; Amini et al., 2007; Reepmeyer et al., 1975). Halo- and dihaloimidazoles form salts with mineral acids and picrates. The nitrates and picrates, which crystallize readily from water and alcohols, are quite often used for the additional characterization of compounds being studied. In this paper, we report the structure determination of 4,5-dibromo-1,2-dimethyl-1H-imidazolium bromide (I) resulting from an unexpected reaction of 1,2-dimethyl-1H-imidazole with bromine in acetone in a modified Ortoleva-King conditions reaction (King, 1944).

The molecular structure of (I) is shown in Fig. 1. The asymmetric unit of title molecule, (C₅H₇N₂Br₂)⁺, Br^-, contains a 4,5-dibromo-1,2-dimethylimidazolium cation and bromide anion linked by an intermolecular N—H···Br hydrogen bond. The crystal packing can be described as intercalated layers parallel to (102) in which bromide ions are located between cations (Fig. 2). Further stabilization is provided by weak intermoleculer C—H···Br hydrogen bonds (Fig. 3).

Experimental

Compound (I) was obtained from reaction of 4,5-dibromo-1,2-dimethyl-1H-imidazole dissolved in acetone with 1 eq. of bromine. After stirring at 303K during 1 h, a colorless suspension was obtained and a white solid was filtered off. A suitable crystal was obtained by slow evaporation at room temperature of a solution of (I) in a MeOH/CHCl₃ mixture.

Refinement

H atoms were located in difference Fourier maps but introduced in calculated positions and treated as riding on their parent C or N atom (with C—H = 0.96 Å, N—H = 0.88 Å and U_iso(H) = 1.5U_eq(C) or 1.2U_eq(N).

Figures

Fig. 1.

The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level.

Fig. 2.

Part of the crystal structure viewed along the b axis.

Fig. 3.

Part of the crystal structure showing hydrogen bonds [N—H···Br (in red), C—H···Br (in blue)] as dashed lines.

Crystal data

C5H7Br2N2+·Br−	F(000) = 624
Mr = 334.86	Dx = 2.52 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3086 reflections
a = 5.5938 (3) Å	θ = 2.9–27.5°
b = 11.2522 (6) Å	µ = 13.64 mm−1
c = 14.4864 (9) Å	T = 150 K
β = 104.571 (3)°	Prism, colourless
V = 882.48 (9) Å3	0.31 × 0.22 × 0.17 mm
Z = 4

Data collection

Bruker APEXII diffractometer	1747 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.050
CCD rotation images, thin slices scans	θmax = 27.5°, θmin = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2002)	h = −6→7
Tmin = 0.058, Tmax = 0.098	k = −14→12
7565 measured reflections	l = −18→17
2032 independent reflections

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.027	H-atom parameters constrained
wR(F2) = 0.060	w = 1/[σ2(Fo2) + (0.0201P)2 + 0.142P] where P = (Fo2 + 2Fc2)/3
S = 1.03	(Δ/σ)max = 0.002
2032 reflections	Δρmax = 0.63 e Å−3
94 parameters	Δρmin = −0.86 e Å−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0075 (4)

Special details

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 > σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.52217 (6)	0.60967 (3)	0.40218 (2)	0.01621 (11)
Br2	0.12689 (6)	0.86245 (3)	0.44145 (2)	0.01726 (11)
N2	0.7783 (5)	0.7167 (2)	0.57813 (19)	0.0142 (6)
N5	0.5520 (5)	0.8641 (3)	0.5998 (2)	0.0171 (6)
H5	0.4987	0.9266	0.6251	0.021*
C1	0.7626 (6)	0.8069 (3)	0.6365 (2)	0.0163 (7)
C3	0.5709 (6)	0.7178 (3)	0.5019 (2)	0.0141 (7)
C4	0.4301 (6)	0.8096 (3)	0.5154 (2)	0.0140 (7)
C6	0.9445 (7)	0.8397 (3)	0.7253 (2)	0.0222 (8)
H6A	0.9879	0.7706	0.7647	0.033*
H6B	0.8745	0.8986	0.7587	0.033*
H6C	1.0896	0.8713	0.7103	0.033*
C7	0.9765 (7)	0.6294 (3)	0.5945 (3)	0.0214 (8)
H7A	1.1062	0.6531	0.6483	0.032*
H7B	1.0403	0.6242	0.5390	0.032*
H7C	0.9137	0.5532	0.6069	0.032*
Br3	0.58756 (6)	0.58078 (3)	0.77871 (2)	0.01713 (12)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0170 (2)	0.01589 (19)	0.01515 (19)	0.00097 (14)	0.00295 (14)	−0.00101 (12)
Br2	0.01324 (19)	0.0185 (2)	0.01989 (19)	0.00293 (14)	0.00389 (14)	0.00221 (13)
N2	0.0086 (14)	0.0175 (15)	0.0156 (14)	−0.0021 (12)	0.0013 (11)	0.0037 (11)
N5	0.0193 (16)	0.0141 (15)	0.0185 (15)	−0.0040 (12)	0.0060 (12)	−0.0026 (11)
C1	0.0153 (18)	0.0171 (18)	0.0162 (17)	−0.0055 (14)	0.0031 (14)	0.0020 (14)
C3	0.0124 (17)	0.0172 (17)	0.0123 (16)	−0.0017 (14)	0.0022 (13)	0.0011 (13)
C4	0.0107 (17)	0.0173 (18)	0.0138 (16)	−0.0015 (14)	0.0029 (13)	−0.0020 (13)
C6	0.021 (2)	0.025 (2)	0.0182 (18)	−0.0087 (16)	0.0008 (15)	−0.0019 (15)
C7	0.0156 (19)	0.023 (2)	0.024 (2)	0.0058 (15)	0.0019 (16)	0.0075 (14)
Br3	0.0163 (2)	0.0161 (2)	0.01874 (19)	−0.00155 (13)	0.00405 (14)	−0.00052 (13)

Geometric parameters (Å, º)

Br1—C3	1.855 (3)	C1—C6	1.472 (5)
Br2—C4	1.861 (3)	C3—C4	1.343 (5)
N2—C1	1.338 (4)	C6—H6A	0.9600
N2—C3	1.386 (4)	C6—H6B	0.9600
N2—C7	1.456 (4)	C6—H6C	0.9600
N5—C1	1.329 (4)	C7—H7A	0.9600
N5—C4	1.385 (4)	C7—H7B	0.9600
N5—H5	0.8800	C7—H7C	0.9600
C1—N2—C3	108.8 (3)	N5—C4—Br2	122.8 (2)
C1—N2—C7	125.3 (3)	C1—C6—H6A	109.5
C3—N2—C7	125.9 (3)	C1—C6—H6B	109.5
C1—N5—C4	109.2 (3)	H6A—C6—H6B	109.5
C1—N5—H5	125.4	C1—C6—H6C	109.5
C4—N5—H5	125.4	H6A—C6—H6C	109.5
N5—C1—N2	107.9 (3)	H6B—C6—H6C	109.5
N5—C1—C6	125.2 (3)	N2—C7—H7A	109.5
N2—C1—C6	127.0 (3)	N2—C7—H7B	109.5
C4—C3—N2	107.1 (3)	H7A—C7—H7B	109.5
C4—C3—Br1	129.9 (2)	N2—C7—H7C	109.5
N2—C3—Br1	123.0 (2)	H7A—C7—H7C	109.5
C3—C4—N5	107.0 (3)	H7B—C7—H7C	109.5
C3—C4—Br2	130.2 (2)
C4—N5—C1—N2	−0.3 (4)	C1—N2—C3—Br1	178.4 (2)
C4—N5—C1—C6	179.1 (3)	C7—N2—C3—Br1	−3.8 (5)
C3—N2—C1—N5	0.4 (4)	N2—C3—C4—N5	0.0 (4)
C7—N2—C1—N5	−177.4 (3)	Br1—C3—C4—N5	−178.5 (2)
C3—N2—C1—C6	−179.0 (3)	N2—C3—C4—Br2	−179.7 (2)
C7—N2—C1—C6	3.2 (5)	Br1—C3—C4—Br2	1.7 (5)
C1—N2—C3—C4	−0.2 (4)	C1—N5—C4—C3	0.2 (4)
C7—N2—C3—C4	177.5 (3)	C1—N5—C4—Br2	180.0 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N5—H5···Br3i	0.88	2.35	3.216 (3)	168
C6—H6A···Br2ii	0.96	2.90	3.796 (3)	156

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