3,3'-Di-n-propyl-1,1'-[p-phenyl-enebis(methyl-ene)]diimidazolium dibromide.

The asymmetric unit of the title compound, C(20)H(28)N(4) (2+)·2Br(-), consists of half a 3,3'-di-n-propyl-1,1'-[p-phenyl-enenis(methyl-ene)]diimidazolium cation and a bromide anion. The cation is located on an inversion center and adopts an ⋯AAA⋯ trans conformation. In the crystal, the cation is linked to the anions via weak C-H⋯Br hydrogen bonds.

Related literature

For details of N-heterocyclic carbenes, see: Herrmann et al. (1998 ▶); Zhang & Trudell (2000 ▶); Lee et al. (2004 ▶). For structures with similar ⋯AAA⋯ trans conformations, see: Chen et al. (2007 ▶); Cheng et al. (2009 ▶).

Experimental

Crystal data

C20H28N4 2+·2Br−

M = 484.28

Monoclinic,

a = 8.9420 (2) Å

b = 11.2443 (2) Å

c = 11.3536 (2) Å

β = 109.716 (1)°

V = 1074.64 (4) Å3

Z = 2

Mo Kα radiation

μ = 3.78 mm−1

T = 296 K

0.37 × 0.35 × 0.30 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.338, T max = 0.397

11799 measured reflections

3127 independent reflections

2409 reflections with I > 2σ(I)

R int = 0.030

Refinement

R[F 2 > 2σ(F 2)] = 0.030

wR(F 2) = 0.078

S = 1.04

3127 reflections

118 parameters

H-atom parameters constrained

Δρmax = 0.30 e Å−3

Δρmin = −0.59 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811026146/lh5273sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811026146/lh5273Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536811026146/lh5273Isup3.cml

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

C20H28N42+·2Br−	F(000) = 492
Mr = 484.28	Dx = 1.497 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4287 reflections
a = 8.9420 (2) Å	θ = 2.4–29.8°
b = 11.2443 (2) Å	µ = 3.78 mm−1
c = 11.3536 (2) Å	T = 296 K
β = 109.716 (1)°	Block, colourless
V = 1074.64 (4) Å3	0.37 × 0.35 × 0.30 mm
Z = 2

Bruker SMART APEXII CCD area-detector diffractometer	3127 independent reflections
Radiation source: fine-focus sealed tube	2409 reflections with I > 2σ(I)
graphite	Rint = 0.030
φ and ω scans	θmax = 30.1°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −12→12
Tmin = 0.338, Tmax = 0.397	k = −15→15
11799 measured reflections	l = −11→16

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) = 0.078	H-atom parameters constrained
S = 1.04	w = 1/[σ2(Fo2) + (0.0366P)2 + 0.234P] where P = (Fo2 + 2Fc2)/3
3127 reflections	(Δ/σ)max < 0.001
118 parameters	Δρmax = 0.30 e Å−3
0 restraints	Δρmin = −0.59 e Å−3

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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	0.24338 (3)	0.428391 (17)	0.069769 (19)	0.04870 (9)
N1	0.06730 (17)	0.72483 (12)	0.28704 (13)	0.0340 (3)
N2	0.28760 (18)	0.76133 (14)	0.25525 (15)	0.0389 (3)
C1	−0.0905 (2)	0.60075 (16)	0.49714 (17)	0.0358 (4)
H1A	−0.1508	0.6684	0.4960	0.043*
C2	0.0537 (2)	0.47667 (16)	0.40181 (16)	0.0350 (4)
H2A	0.0907	0.4608	0.3360	0.042*
C3	−0.03759 (19)	0.57747 (14)	0.39781 (16)	0.0316 (3)
C4	−0.0764 (2)	0.66197 (17)	0.28836 (18)	0.0383 (4)
H4A	−0.1216	0.6179	0.2110	0.046*
H4B	−0.1547	0.7193	0.2941	0.046*
C5	0.1346 (2)	0.82204 (16)	0.35896 (17)	0.0401 (4)
H5A	0.0933	0.8639	0.4116	0.048*
C6	0.2712 (2)	0.84497 (16)	0.33885 (18)	0.0427 (4)
H6A	0.3420	0.9061	0.3747	0.051*
C7	0.1620 (2)	0.68965 (16)	0.22476 (17)	0.0370 (4)
H7A	0.1434	0.6259	0.1695	0.044*
C8	0.4185 (2)	0.75295 (18)	0.2048 (2)	0.0456 (4)
H8A	0.4123	0.6772	0.1625	0.055*
H8B	0.5189	0.7557	0.2732	0.055*
C9	0.4132 (2)	0.85232 (19)	0.1143 (2)	0.0469 (5)
H9A	0.4181	0.9283	0.1558	0.056*
H9B	0.3139	0.8488	0.0446	0.056*
C10	0.5517 (3)	0.8419 (2)	0.0657 (2)	0.0586 (6)
H10A	0.5471	0.9058	0.0085	0.088*
H10B	0.5457	0.7672	0.0234	0.088*
H10C	0.6499	0.8462	0.1347	0.088*

	U11	U22	U33	U12	U13	U23
Br1	0.06110 (15)	0.03539 (11)	0.05110 (14)	0.00544 (9)	0.02086 (10)	0.00409 (8)
N1	0.0411 (8)	0.0308 (7)	0.0319 (7)	−0.0010 (6)	0.0149 (6)	0.0013 (6)
N2	0.0424 (8)	0.0354 (7)	0.0417 (9)	−0.0021 (6)	0.0176 (7)	−0.0004 (6)
C1	0.0370 (9)	0.0318 (8)	0.0416 (10)	0.0037 (7)	0.0173 (8)	0.0001 (7)
C2	0.0386 (9)	0.0355 (8)	0.0352 (9)	0.0020 (7)	0.0181 (8)	−0.0010 (7)
C3	0.0301 (8)	0.0311 (8)	0.0337 (8)	−0.0039 (6)	0.0109 (7)	0.0001 (7)
C4	0.0357 (9)	0.0406 (9)	0.0382 (10)	−0.0003 (7)	0.0119 (7)	0.0036 (8)
C5	0.0552 (11)	0.0329 (8)	0.0333 (9)	0.0016 (8)	0.0165 (8)	−0.0023 (7)
C6	0.0522 (11)	0.0349 (9)	0.0397 (10)	−0.0072 (8)	0.0138 (9)	−0.0035 (8)
C7	0.0456 (10)	0.0319 (8)	0.0361 (9)	−0.0015 (7)	0.0171 (8)	−0.0009 (7)
C8	0.0416 (10)	0.0456 (10)	0.0545 (12)	0.0018 (8)	0.0224 (9)	0.0055 (9)
C9	0.0471 (11)	0.0496 (11)	0.0484 (11)	0.0004 (9)	0.0219 (9)	0.0047 (9)
C10	0.0566 (13)	0.0693 (15)	0.0598 (14)	−0.0037 (11)	0.0326 (11)	0.0048 (12)

N1—C7	1.333 (2)	C4—H4B	0.9700
N1—C5	1.376 (2)	C5—C6	1.341 (3)
N1—C4	1.471 (2)	C5—H5A	0.9300
N2—C7	1.330 (2)	C6—H6A	0.9300
N2—C6	1.379 (2)	C7—H7A	0.9300
N2—C8	1.470 (2)	C8—C9	1.508 (3)
C1—C3	1.387 (2)	C8—H8A	0.9700
C1—C2i	1.388 (3)	C8—H8B	0.9700
C1—H1A	0.9300	C9—C10	1.521 (3)
C2—C1i	1.388 (3)	C9—H9A	0.9700
C2—C3	1.389 (2)	C9—H9B	0.9700
C2—H2A	0.9300	C10—H10A	0.9600
C3—C4	1.509 (2)	C10—H10B	0.9600
C4—H4A	0.9700	C10—H10C	0.9600
C7—N1—C5	108.76 (15)	C5—C6—N2	107.47 (16)
C7—N1—C4	125.17 (15)	C5—C6—H6A	126.3
C5—N1—C4	125.78 (14)	N2—C6—H6A	126.3
C7—N2—C6	108.44 (15)	N2—C7—N1	108.29 (15)
C7—N2—C8	124.99 (16)	N2—C7—H7A	125.9
C6—N2—C8	126.56 (16)	N1—C7—H7A	125.9
C3—C1—C2i	120.18 (16)	N2—C8—C9	111.85 (16)
C3—C1—H1A	119.9	N2—C8—H8A	109.2
C2i—C1—H1A	119.9	C9—C8—H8A	109.2
C1i—C2—C3	120.77 (16)	N2—C8—H8B	109.2
C1i—C2—H2A	119.6	C9—C8—H8B	109.2
C3—C2—H2A	119.6	H8A—C8—H8B	107.9
C1—C3—C2	119.05 (16)	C8—C9—C10	110.34 (17)
C1—C3—C4	120.26 (15)	C8—C9—H9A	109.6
C2—C3—C4	120.68 (15)	C10—C9—H9A	109.6
N1—C4—C3	110.61 (14)	C8—C9—H9B	109.6
N1—C4—H4A	109.5	C10—C9—H9B	109.6
C3—C4—H4A	109.5	H9A—C9—H9B	108.1
N1—C4—H4B	109.5	C9—C10—H10A	109.5
C3—C4—H4B	109.5	C9—C10—H10B	109.5
H4A—C4—H4B	108.1	H10A—C10—H10B	109.5
C6—C5—N1	107.04 (16)	C9—C10—H10C	109.5
C6—C5—H5A	126.5	H10A—C10—H10C	109.5
N1—C5—H5A	126.5	H10B—C10—H10C	109.5
C2i—C1—C3—C2	−0.7 (3)	N1—C5—C6—N2	−0.3 (2)
C2i—C1—C3—C4	−179.54 (16)	C7—N2—C6—C5	0.5 (2)
C1i—C2—C3—C1	0.7 (3)	C8—N2—C6—C5	179.06 (17)
C1i—C2—C3—C4	179.54 (16)	C6—N2—C7—N1	−0.4 (2)
C7—N1—C4—C3	92.7 (2)	C8—N2—C7—N1	−179.02 (16)
C5—N1—C4—C3	−80.3 (2)	C5—N1—C7—N2	0.2 (2)
C1—C3—C4—N1	110.19 (18)	C4—N1—C7—N2	−173.88 (15)
C2—C3—C4—N1	−68.6 (2)	C7—N2—C8—C9	107.5 (2)
C7—N1—C5—C6	0.1 (2)	C6—N2—C8—C9	−70.9 (2)
C4—N1—C5—C6	174.13 (16)	N2—C8—C9—C10	179.05 (18)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···Br1	0.93	2.77	3.6222 (18)	152

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7A⋯Br1	0.93	2.77	3.6222 (18)	152