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The asymmetric unit of the title compound, C17H13N4+·BF4, contains one half of the benzimidazolium cation and one half of the tetra­fluoridoborate anion, with crystallographic mirror planes bis­ecting the mol­ecules. One F atom of the tetra­fluoridoborate is equally disordered about a crystallographic mirror plane. In the crystal, C—H...F inter­actions link the cations and anions into layers parallel to (100). The crystal packing is further stabilized by F...π contacts involving the tetra­fluoridoborate anions and the five-membered rings [F...centroid = 2.811 (2) Å].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536811027942/su2291sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536811027942/su2291Isup2.hkl
Contains datablock I

cml

Chemical Markup Language (CML) file https://doi.org/10.1107/S1600536811027942/su2291Isup3.cml
Supplementary material

CCDC reference: 841244

Key indicators

  • Single-crystal X-ray study
  • T = 183 K
  • Mean [sigma](C-C) = 0.002 Å
  • Disorder in solvent or counterion
  • R factor = 0.042
  • wR factor = 0.117
  • Data-to-parameter ratio = 15.5

checkCIF/PLATON results

No syntax errors found



Alert level A DIFF020_ALERT_1_A _diffrn_standards_interval_count and _diffrn_standards_interval_time are missing. Number of measurements between standards or time (min) between standards. DIFF022_ALERT_1_A _diffrn_standards_decay_% is missing Percentage decrease in standards intensity.
Alert level C PLAT244_ALERT_4_C Low 'Solvent' Ueq as Compared to Neighbors of B1 PLAT480_ALERT_4_C Long H...A H-Bond Reported H9 .. F1 .. 2.62 Ang. PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) ..... 2
Alert level G PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF .... ? PLAT302_ALERT_4_G Note: Anion/Solvent Disorder ................... 20 Perc. PLAT432_ALERT_2_G Short Inter X...Y Contact F2 .. C2 .. 2.94 Ang.
2 ALERT level A = Most likely a serious problem - resolve or explain 0 ALERT level B = A potentially serious problem, consider carefully 3 ALERT level C = Check. Ensure it is not caused by an omission or oversight 3 ALERT level G = General information/check it is not something unexpected 2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 3 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

Comment top

N,N'-bis(2-pyridyl)aryldiamines are an important class of compounds that are useful as intermediates in the syntheses of organic electroluminescent devices (LED) (Stoessel et al., 2010), or as compounds useful for altering the lifespan of eukaryotic organisms in the yeast (Goldfarb, 2009). Imidazolium salts based on the benzoimidazole scaffold are used in electronics (Bold et al., 2005; Murakami et al., 2007) and in catalytic processes involving the use of the benzimidazolium salt as it is (Teles et al., 1996), or bound to a metal (Berlin et al., 2007; Huang et al., 2005).

We used the N,N'-bis(2-pyridyl)-benzene-1,2-diamine compound as a starting material for the synthesis of the title compound, a new imidazolium salt. Despite the fact that the synthesis of the starting material N,N'-bis(pyridin-2-yl)benzene-1,2-diamine had been reported previously (Gdaniec et al., 2004), we optimized the procedure to obtain a better yield (91 instead of 70%) using the reaction reported in the Experimental section (Fig. 4) with a microwave technique. A similar procedure was succesfully used to synthesize the title compound in a very high yield (99.7%). It is the first example of a coupling between a halo pyridine and an aniline made with microwave heating that does not imply the use of any metal. This method to couple halo pyridines and anilines can be very useful to produce compounds with pharmaceutical activity since many pharmaceuticals are based on the aniline-pyridine scaffold (Kim et al., 1996; Wu et al., 2001).

The asymmetric unit of the title compound, C17H13N4+.BF4-, contains one half-molecule of the benzimidazolium cation and one half-molecule of the anion, crystallographic mirror planes bisecting the molecules (Fig. 1). One F atom of the tetrafluoroborate is disordered over two positions. The second position being generated by a crystallographic mirror plane, the site-occupancy factor is 0.5. The benzimidazole and pyridine rings are not coplanar, the dihedral angle between the mean planes is 26.67 (4)°.

In the crystal intermolecular C—H···F interactions link the cations and anions into layers parallel to the (100) crystallographic plane (Fig. 2, Table 1). The crystal packing is further stabilizes by F···π contacts (Fig. 3) involving the tetrafluoridoborate anions and the five-membered rings of the benzimidazole rings [F···centroid = 2.811 (2) Å].

Related literature top

For background to applications of N,N'-bis(2-pyridyl)aryldiamines, see: Stoessel et al. (2010); Goldfarb (2009) and to applications of imidazolium salts, see: Berlin et al. (2007); Bold et al. (2005); Huang et al. (2005); Murakami et al. (2007); Teles et al. (1996). For pharmaceuticals based on the aniline–pyridine scaffold, see: Kim et al. (1996); Wu et al. (2001). For the synthesis of the starting material N,N'-bis(pyridin-2-yl)benzene-1,2-diamine, see: Gdaniec et al. (2004).

Experimental top

To benzene-1,2-diamine (2.7 g, 24.97 mmol) in a microwave vial, 2-chloropyridine (9 ml, 46.95 mmol) was added. The vial was then closed with a cap consisting of a Teflon septum and the reaction mixture was heated for 35 mins at 458 K. Monitoring with TLC (thin layer chromatography) and GC—MS (gas chromatography - mass spectrometry) showed that the benzene-1,2-diamine was consumed after this time and the mixture was allowed to cool to room temperature. The crude mixture was dissolved in water (15 ml) and dropped into a solution of concentrated ammonia in water (25 ml of NH4OH 24.5% in 250 ml of water). The resulting pink-red precipitate was filtered off, washed with water (50 ml) and was subsequently dried in air to give N,N'-bis(pyridin-2-yl)benzene-1,2-diamine. Further recrystallization from ethanol gave a very pure product (yield: 2.902 g, 91%).

To N,N'-bis(pyridin-2-yl)benzene-1,2-diamine (500 mg, 1.91 mmol) in a microwave vial, finely ground ammonium tetrafluoroborate (204 mg, 1.91 mmol) was added followed by the triethyl orthoformate (10 ml, 59 mmol). The vial with the red pink suspension was then closed with a cap consisting of a Teflon septum and the reaction mixture was heated for 25 minutes at 413 K and then for further 20 minutes to 433 K. After that time inside the vial a blue-violet solid was present and TLC analysis showed that the starting material had been consumed. The solid was separated off and then stirred with ethyl acetate (3x50 ml) for 15 minutes. It was then collected by suction filtration, washed with diethyl ether and dried to afford a deep violet-blue compound (yield: 686 mg, 99.7%). Recrystallization from a hot saturated solution of water/methanol (9/2) afforded red plate-like crystals of the title compound, suitable for X-ray analysis. Spectroscopic data for the title compound are given in the archived CIF.

Refinement top

One F atom of the tetrafluoroborate ion is disordered over two positions around a mirror plane (site-occupancy factor of 1/2). H-atom H1 was located in a difference Fourier map and was freely refined. The C-bound H-atoms were included in calculated positions and treated as riding atoms: C—H = 0.93 Å with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006), ORTEP-3 for Windows (Farrugia, 1997) and POV-RAY for Windows (Cason, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with the numbering scheme and displacement ellipsoids drawn at the 50% probability level (H-atoms are shown as spheres of arbitrary size). Symmetry code: (i) -x + 3/2, -y, z - 1/2.
[Figure 2] Fig. 2. View normal to (100) of the two-dimensional network of the title compound, formed by intermolecular C—H···F interactions (dashed lines; see Table 1 for details).
[Figure 3] Fig. 3. View normal to (001) of the three-dimensional network of the title compound, formed by intermolecular B—F···π interactions (dashed lines; see Comment section for details).
[Figure 4] Fig. 4. Reaction scheme.
1,3-Bis(pyridin-2-yl)-1H-benzimidazol-3-ium tetrafluoridoborate top
Crystal data top
C17H13N4+·BF4F(000) = 736
Mr = 360.12Dx = 1.52 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 4054 reflections
a = 7.3412 (2) Åθ = 2.8–32.6°
b = 17.5051 (5) ŵ = 0.13 mm1
c = 12.2426 (3) ÅT = 183 K
V = 1573.28 (7) Å3Plate, red
Z = 40.44 × 0.31 × 0.11 mm
Data collection top
Oxford Diffraction Xcalibur
diffractometer with a Ruby detector
1543 reflections with I > 2σ(I)
ω scansRint = 0.022
Absorption correction: analytical
[CrysAlis PRO (Oxford Diffraction, 2010) based on expressions derived by Clark & Reid (1995)]
θmax = 28.3°, θmin = 3.2°
Tmin = 0.964, Tmax = 0.991h = 99
8816 measured reflectionsk = 2023
2014 independent reflectionsl = 1216
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.042 w = 1/[σ2(Fo2) + (0.062P)2 + 0.2418P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.117(Δ/σ)max < 0.001
S = 1.08Δρmax = 0.27 e Å3
2014 reflectionsΔρmin = 0.36 e Å3
130 parameters
Crystal data top
C17H13N4+·BF4V = 1573.28 (7) Å3
Mr = 360.12Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 7.3412 (2) ŵ = 0.13 mm1
b = 17.5051 (5) ÅT = 183 K
c = 12.2426 (3) Å0.44 × 0.31 × 0.11 mm
Data collection top
Oxford Diffraction Xcalibur
diffractometer with a Ruby detector
2014 independent reflections
Absorption correction: analytical
[CrysAlis PRO (Oxford Diffraction, 2010) based on expressions derived by Clark & Reid (1995)]
1543 reflections with I > 2σ(I)
Tmin = 0.964, Tmax = 0.991Rint = 0.022
8816 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.117H atoms treated by a mixture of independent and constrained refinement
S = 1.08Δρmax = 0.27 e Å3
2014 reflectionsΔρmin = 0.36 e Å3
130 parameters
Special details top

Experimental. Spectroscopic data for the title compound:

1H-NMR in CD3CN: δ = 10.07 (s, 1H), δ = 8.837 (dd, 2H), δ = 8.48 (m, 2H), δ = 8.29 (m,2H), δ = 8.04 (t, 1H), δ = 8.01 (t, 1H), δ = 7.87 (m, 2H) δ = 7.77 (m, 2H).

13C-NMR in CD3CN: δ = 150.95, 141.60, 129.49, 126.93, 118.83, 118.26,116.86.

19F-NMR in CD3CN: δ = -152.32.

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
C10.7110 (2)0.250.56060 (15)0.0232 (4)
C20.64692 (16)0.21032 (7)0.39260 (10)0.0211 (3)
C30.60860 (17)0.16850 (8)0.29898 (10)0.0243 (3)
H30.60880.11540.2990.029*
C40.57020 (17)0.20992 (8)0.20603 (11)0.0263 (3)
H40.54360.18410.14160.032*
C50.69854 (17)0.11073 (8)0.53968 (11)0.0245 (3)
C60.6441 (2)0.09450 (9)0.64542 (12)0.0336 (3)
H60.60260.13240.69250.04*
C70.6546 (2)0.01864 (9)0.67741 (13)0.0397 (4)
H70.6220.00450.7480.048*
C80.7136 (2)0.03573 (9)0.60414 (14)0.0374 (4)
H80.71920.0870.6240.045*
C90.7640 (2)0.01265 (8)0.50081 (14)0.0345 (4)
H90.80380.04960.45170.041*
N10.68805 (14)0.18768 (6)0.49998 (9)0.0223 (3)
N20.75864 (17)0.06028 (7)0.46749 (10)0.0302 (3)
F10.58623 (16)0.18658 (7)0.89742 (12)0.0763 (4)
F20.8041 (3)0.2711 (2)0.98569 (15)0.0680 (16)0.5
F30.8073 (2)0.250.80661 (11)0.0577 (4)
B10.6969 (3)0.250.89769 (19)0.0338 (5)
H10.743 (3)0.250.6360 (19)0.024 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0249 (9)0.0230 (10)0.0217 (9)00.0010 (7)0
C20.0210 (6)0.0224 (7)0.0200 (6)0.0008 (5)0.0019 (5)0.0021 (5)
C30.0254 (6)0.0229 (7)0.0245 (7)0.0016 (5)0.0012 (5)0.0029 (5)
C40.0263 (6)0.0313 (7)0.0212 (6)0.0013 (5)0.0002 (5)0.0043 (5)
C50.0257 (6)0.0215 (7)0.0263 (7)0.0014 (5)0.0046 (5)0.0030 (5)
C60.0450 (8)0.0289 (8)0.0269 (7)0.0052 (6)0.0002 (6)0.0010 (6)
C70.0521 (9)0.0371 (9)0.0297 (7)0.0092 (7)0.0045 (7)0.0114 (7)
C80.0416 (9)0.0249 (8)0.0457 (9)0.0009 (6)0.0092 (7)0.0117 (7)
C90.0388 (8)0.0235 (8)0.0411 (8)0.0055 (6)0.0036 (6)0.0020 (6)
N10.0258 (5)0.0211 (6)0.0200 (5)0.0001 (4)0.0006 (4)0.0015 (4)
N20.0353 (6)0.0230 (6)0.0325 (6)0.0033 (5)0.0002 (5)0.0019 (5)
F10.0558 (7)0.0436 (7)0.1295 (12)0.0010 (5)0.0195 (7)0.0143 (7)
F20.0400 (9)0.132 (5)0.0315 (9)0.0042 (12)0.0083 (7)0.0174 (14)
F30.0646 (10)0.0810 (12)0.0276 (7)00.0114 (6)0
B10.0284 (11)0.0494 (16)0.0236 (11)00.0016 (9)0
Geometric parameters (Å, º) top
C1—N11.3302 (15)C6—C71.387 (2)
C1—H10.95 (2)C6—H60.93
C2—C31.3887 (18)C7—C81.378 (2)
C2—C2i1.389 (3)C7—H70.93
C2—N11.4060 (16)C8—C91.379 (2)
C3—C41.3784 (18)C8—H80.93
C3—H30.93C9—N21.3408 (19)
C4—C4i1.403 (3)C9—H90.93
C4—H40.93F1—B11.3756 (18)
C5—N21.3249 (18)F2—B11.384 (3)
C5—C61.384 (2)F3—B11.379 (3)
C5—N11.4341 (17)
N1—C1—N1i110.20 (16)C8—C7—H7120.2
N1—C1—H1124.88 (9)C6—C7—H7120.2
N1i—C1—H1124.88 (9)C7—C8—C9118.64 (14)
C3—C2—C2i121.81 (8)C7—C8—H8120.7
C3—C2—N1131.81 (12)C9—C8—H8120.7
C2i—C2—N1106.37 (7)N2—C9—C8123.39 (15)
C4—C3—C2116.46 (13)N2—C9—H9118.3
C4—C3—H3121.8C8—C9—H9118.3
C2—C3—H3121.8C1—N1—C2108.53 (11)
C3—C4—C4i121.74 (8)C1—N1—C5125.06 (12)
C3—C4—H4119.1C2—N1—C5126.39 (11)
C4i—C4—H4119.1C5—N2—C9116.19 (13)
N2—C5—C6125.68 (13)F1—B1—F1i107.61 (19)
N2—C5—N1114.70 (12)F1—B1—F3110.21 (13)
C6—C5—N1119.61 (12)F1—B1—F2i97.01 (18)
C5—C6—C7116.38 (14)F1—B1—F2123.6 (2)
C5—C6—H6121.8F1i—B1—F297.01 (18)
C7—C6—H6121.8F3—B1—F2107.17 (18)
C8—C7—C6119.69 (14)
Symmetry code: (i) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···F30.95 (2)2.14 (2)3.094 (2)178 (2)
C9—H9···F1ii0.932.623.4759 (19)154
Symmetry code: (ii) x+3/2, y, z1/2.

Experimental details

Crystal data
Chemical formulaC17H13N4+·BF4
Mr360.12
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)183
a, b, c (Å)7.3412 (2), 17.5051 (5), 12.2426 (3)
V3)1573.28 (7)
Z4
Radiation typeMo Kα
µ (mm1)0.13
Crystal size (mm)0.44 × 0.31 × 0.11
Data collection
DiffractometerOxford Diffraction Xcalibur
diffractometer with a Ruby detector
Absorption correctionAnalytical
[CrysAlis PRO (Oxford Diffraction, 2010) based on expressions derived by Clark & Reid (1995)]
Tmin, Tmax0.964, 0.991
No. of measured, independent and
observed [I > 2σ(I)] reflections
8816, 2014, 1543
Rint0.022
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.117, 1.08
No. of reflections2014
No. of parameters130
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.27, 0.36

Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2006), ORTEP-3 for Windows (Farrugia, 1997) and POV-RAY for Windows (Cason, 2003), WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···F30.95 (2)2.14 (2)3.094 (2)178.4 (18)
C9—H9···F1i0.932.623.4759 (19)154
Symmetry code: (i) x+3/2, y, z1/2.
 

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