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The title compound, C5H6N+·CF3SO3, was serendipitously crystallized in the chiral space group P43212. The component entities associate into hydrogen-bonded helical chains, which propagate along the a and b axes of the crystal, with an alternating disposition of the cations and anions along the chain. N—H...O charge-assisted hydrogen bonds, from each pyridinium cation to two adjacent trifluoro­methane­sulfonate anions and from every anion to two different cations, direct the formation of the supra­molecular chiral arrays. The crystal packing exhibits nonconventional C—H...O and C—H...F hydrogen bonds between the components. The observed structure demonstrates induction of supra­molecular chirality by a combination of Coulombic attractions and inter­molecular hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109034866/ga3132sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270109034866/ga3132Isup2.hkl
Contains datablock I

CCDC reference: 755984

Comment top

Pyridinium trifluoromethanesulfonate is a common commercially available reagent used in chemical syntheses, in particular as a convenient source for the trifluoromethanesulfonate anion. However, the crystal structure of this compound alone has never been reported, and the simultaneous incorporation of its two components into crystals of other compounds has been rarely observed (Salmon et al., 2006, 2007; Cambridge Structural Database, Version 5.30; Allen, 2002). Crystals of pure pyridinium trifluoromethanesulfonate, (I), were obtained by serendipity. The uniquely interesting features of the resulting structure provided, however, an adequate justification of its more detailed analysis, which relates to our recent efforts on the supramolecular synthesis of chiral architectures from achiral building blocks using hydrogen and halogen bonds (Muniappan et al., 2008; Lipstman et al., 2008; George & Goldberg, 2006; George et al., 2006; Vinodu & Goldberg, 2005). Induction of supramolecular chirality in crystals of achiral salts as well as neutral compounds has received considerable attention in recent years owing to its potential significance to optical resolution and asymmetric synthesis (e.g. Tanaka et al., 2006; Perez-Garcia & Amabilino, 2007).

An ORTEPIII (Burnett & Johnson, 1996) representation of (I) is shown in Fig. 1. This simple structure is of particular interest because of the variety of intermolecular interactions that operate in it and because it is possible to evaluate their relative contributions to the supramolecular organization. It is evident that Coulombic forces and N—H···O hydrogen bonds play a major role to this end. Firstly, as in simple AB-type inorganic salts (e.g. halites, sphalerites), optimization of the electrostatic attractions requires an alternating close-packed arrangement of ions bearing opposite charges. Thus, several trifluoromethanesulfonate anions are positioned in the immediate environment of the pyridinium cations, and vice versa (Fig. 2). Secondly, the component species in (I) are prone to charge-assisted hydrogen bonding between them. The cationic species represents a rather strong H-atom donor from the acidic NH+ site. In turn, the O atoms of the negatively charged trifluoromethanesulfonate are excellent H-atom acceptors in hydrogen bonding. Excess of the latter leads to the formation of bifurcated hydrogen bonds, where the pyridinium cation reacts simultaneously with the different O-atom sites of two trifluoromethanesulfonate anions (Fig. 2 and Table 1). Concurrently, every trifluoromethanesulfonate anion is thus involved in hydrogen bonding to two neighboring pyridinium ions, leading to the formation of one-dimensional hydrogen-bonded supramolecular arrays, which propagate in the crystal along the a and b axes of the unit cell (Fig. 3). Optimization of the hydrogen bonding (with each moiety being involved in two such bonds), along with the need for charge neutrality (see above), imparts 21 helicity to the hydrogen-bonded arrays.

The peripheries of the hydrogen-bonded helices described above (see Fig. 3) are linked by C—H bonds involving the aromatic component, as well as by the CF3 residues of the trifluoromethanesulfonate anions. Thus atom O4 of the latter, which is not involved in the N—H···O hydrogen bonding, is also turned outward. Correspondingly, side packing of the helical arrays leads to secondary C—H···O and C—H···F interactions in the interface (Table 1). These nonconventional hydrogen bonds are considered to be attractive, the CH groups being electron deficient while the highly electronegative O and F sites are negatively charged (Desiraju & Steiner, 1999). All the corresponding contact distances (Table 1) are either equal to or slightly longer than the respective sums of the van der Waals radii (Bondi, 1964), reflecting the fact that they are very weak interactions. The shortest intermolecular F···F interaction distances observed in (I) are similar to twice the van der Waals radius of the F atom (1.40–1.47 Å; Bondi, 1964) and may represent very weak interactions (Chopra et al., 2006; Tsuzuki et al., 2003).

In summary, this study characterizes for the first time the unique crystal structure of pure pyridinium trifluoromethanesulfonate and the supramolecular chirality it exhibits. The latter is induced by a combination of nondirectional Coulombic interactions and directional hydrogen bonding between the ionic constituents, leading to the formation of supramolecular arrays of unidirectional helical symmetry. Common van der Waals-type cohesive forces (including the nonconventional hydrogen bonds, which are the `bread-and-butter' of the vast majority of organic crystals) operate in the interfaces between neighboring chains. The chirality of the entire crystalline architecture seems to have been induced by that of the individual chain arrays (Tanaka et al., 2006; Muniappan et al., 2008). The observed structure reflects the hierarchical significance of the Coulombic, hydrogen bonding and van der Waals-type interactions (in this order) with regard to directing the crystallization modes of organic compounds.

Related literature top

For related literature, see: Allen (2002); Bondi (1964); Chopra et al. (2006); Desiraju & Steiner (1999); George & Goldberg (2006); George, Lipstman, Muniappan & Goldberg (2006); Lipstman et al. (2008); Muniappan et al. (2008); Perez-Garcia & Amabilino (2007); Salmon et al. (2006, 2007); Tsuzuki et al. (2003); Vinodu & Goldberg (2005).

Experimental top

Pyridinium trifluoromethanesulfonate was obtained commercially. Colorless crystalline needles [plates in CIF] were obtained by chance when a solution of this compound in a 1:1 dichloromethane:n-hexane mixture was allowed to evaporate slowly. They were characterized by large mosaicity (with a mean value of 1.47°) and weak scattering, which dictated collection of the diffraction frames at 0.3° intervals and limited significant diffraction to 2θmax = 52°.

Refinement top

The atomic coordinates of the H atoms, initially placed in calculated positions, were refined freely, while Uiso(H) values were fixed at 1.2Ueq(C,N).

Computing details top

Data collection: Collect (Nonius, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-III (Burnett & Johnson, 1996) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing the atom-labeling scheme. The atomic ellipsoids represent displacement parameters at the 50% probability level. One hydrogen bond between the component species of the asymmetric unit is indicated by dashed lines.
[Figure 2] Fig. 2. The interactions of a given pyridinium ion with the surrounding species (Table 1) via N—H···O hydrogen bonds and C—H···O and C—H···F interactions (all denoted by dashed lines). [Symmetry codes: (i) x + 1/2, -y + 1/2, -z + 5/4; (ii) y + 3/2, -x + 3/2, z + 1/4; (iii) y + 1/2, -x + 3/2, z + 1/4; (iv) -y + 1, -x + 2, -z + 3/2; (v) x - 1/2, -y + 1/2, -z + 5/4.]
[Figure 3] Fig. 3. The crystal packing of (I), showing the hydrogen-bonded helical chains formed in this structure, with an alternating arrangement of the pyridinium and trifluoromethanesulfonate ions. Chains (i) and (iii) extend along the 21a screw, and chains (ii) and (iv) along the 21b screw axis. The N—H···O hydrogen bonds (Table 1) are indicated by dashed lines. All H atoms have been omitted.
pyridinium trifluoromethanesulfonate top
Crystal data top
C5H6N+·CF3O3SDx = 1.717 Mg m3
Mr = 229.18Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P43212Cell parameters from 1793 reflections
a = 8.5265 (8) Åθ = 2.5–26.0°
c = 24.388 (2) ŵ = 0.40 mm1
V = 1773.0 (3) Å3T = 110 K
Z = 8Plate, colorless
F(000) = 9280.45 × 0.20 × 0.10 mm
Data collection top
Nonius KappaCCD
diffractometer
1222 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.057
Graphite monochromatorθmax = 26.0°, θmin = 2.5°
Detector resolution: 12.8 pixels mm-1h = 1010
0.3 deg. ω scansk = 77
11922 measured reflectionsl = 2927
1752 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.059Only H-atom coordinates refined
wR(F2) = 0.121 w = 1/[σ2(Fo2) + (0.0622P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max = 0.001
1752 reflectionsΔρmax = 0.38 e Å3
145 parametersΔρmin = 0.39 e Å3
0 restraintsAbsolute structure: Flack (1983), 657 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.08 (17)
Crystal data top
C5H6N+·CF3O3SZ = 8
Mr = 229.18Mo Kα radiation
Tetragonal, P43212µ = 0.40 mm1
a = 8.5265 (8) ÅT = 110 K
c = 24.388 (2) Å0.45 × 0.20 × 0.10 mm
V = 1773.0 (3) Å3
Data collection top
Nonius KappaCCD
diffractometer
1222 reflections with I > 2σ(I)
11922 measured reflectionsRint = 0.057
1752 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.059Only H-atom coordinates refined
wR(F2) = 0.121Δρmax = 0.38 e Å3
S = 1.03Δρmin = 0.39 e Å3
1752 reflectionsAbsolute structure: Flack (1983), 657 Friedel pairs
145 parametersAbsolute structure parameter: 0.08 (17)
0 restraints
Special details top

Experimental. The crystals were characterized by high mosaicity, the average value of which was 1.47 /%.

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*/Ueq
S10.96551 (12)0.03340 (12)0.61834 (4)0.0342 (3)
O20.8228 (3)0.1245 (3)0.61932 (11)0.0424 (8)
O31.0986 (3)0.1121 (3)0.64216 (10)0.0422 (8)
O40.9957 (3)0.0454 (3)0.56742 (10)0.0399 (7)
C50.9238 (5)0.1255 (5)0.66632 (16)0.0396 (11)
F60.8861 (3)0.0718 (3)0.71551 (9)0.0556 (8)
F70.8062 (4)0.2132 (3)0.64876 (10)0.0552 (8)
F81.0484 (4)0.2184 (3)0.67217 (10)0.0641 (8)
N91.0581 (5)0.4000 (4)0.70558 (14)0.0396 (10)
H91.092 (5)0.354 (6)0.6782 (17)0.047*
C101.1503 (6)0.4750 (6)0.74135 (18)0.0410 (11)
H101.260 (5)0.476 (5)0.7354 (15)0.049*
C111.0843 (6)0.5605 (6)0.78154 (18)0.0398 (12)
H111.142 (5)0.615 (5)0.8047 (16)0.048*
C120.9232 (5)0.5696 (5)0.78570 (17)0.0404 (12)
H120.876 (5)0.628 (5)0.8113 (16)0.048*
C130.8313 (5)0.4896 (5)0.74839 (19)0.0416 (12)
H130.728 (5)0.490 (5)0.7492 (15)0.050*
C140.9003 (6)0.4047 (5)0.70814 (18)0.0392 (12)
H140.849 (6)0.340 (5)0.6817 (16)0.047*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0351 (6)0.0314 (6)0.0359 (5)0.0006 (5)0.0010 (4)0.0003 (4)
O20.041 (2)0.0359 (19)0.0502 (17)0.0092 (15)0.0074 (14)0.0041 (14)
O30.0365 (19)0.0346 (18)0.0554 (18)0.0074 (15)0.0004 (14)0.0079 (14)
O40.0446 (19)0.0405 (17)0.0344 (14)0.0003 (15)0.0036 (12)0.0003 (12)
C50.041 (3)0.042 (3)0.035 (2)0.001 (3)0.005 (2)0.003 (2)
F60.0659 (19)0.066 (2)0.0346 (13)0.0126 (15)0.0073 (12)0.0035 (12)
F70.060 (2)0.0489 (18)0.0568 (14)0.0227 (15)0.0059 (13)0.0030 (12)
F80.063 (2)0.0573 (19)0.0723 (18)0.0173 (17)0.0068 (15)0.0238 (15)
N90.046 (3)0.040 (2)0.033 (2)0.011 (2)0.0102 (19)0.0001 (17)
C100.032 (2)0.051 (3)0.041 (3)0.003 (2)0.001 (2)0.005 (2)
C110.042 (3)0.041 (3)0.037 (3)0.003 (2)0.006 (2)0.000 (2)
C120.046 (3)0.037 (3)0.037 (3)0.007 (2)0.004 (2)0.004 (2)
C130.030 (2)0.046 (3)0.049 (3)0.003 (2)0.006 (2)0.003 (3)
C140.039 (3)0.036 (3)0.043 (3)0.001 (2)0.001 (2)0.002 (2)
Geometric parameters (Å, º) top
S1—O41.436 (3)C10—C111.345 (6)
S1—O31.441 (3)C10—H100.94 (4)
S1—O21.444 (3)C11—C121.380 (6)
S1—C51.825 (4)C11—H110.88 (4)
C5—F71.322 (5)C12—C131.381 (6)
C5—F61.324 (5)C12—H120.89 (4)
C5—F81.333 (5)C13—C141.354 (6)
N9—C101.337 (6)C13—H130.88 (4)
N9—C141.348 (6)C14—H140.95 (4)
N9—H90.83 (4)
O4—S1—O3115.20 (17)N9—C10—C11119.3 (4)
O4—S1—O2114.67 (17)N9—C10—H10119 (3)
O3—S1—O2113.99 (18)C11—C10—H10121 (3)
O4—S1—C5104.00 (18)C10—C11—C12120.0 (5)
O3—S1—C5103.93 (19)C10—C11—H11121 (3)
O2—S1—C5103.0 (2)C12—C11—H11119 (3)
F7—C5—F6107.8 (3)C11—C12—C13119.2 (4)
F7—C5—F8107.6 (4)C11—C12—H12122 (3)
F6—C5—F8107.6 (4)C13—C12—H12119 (3)
F7—C5—S1111.1 (3)C14—C13—C12119.7 (4)
F6—C5—S1111.8 (3)C14—C13—H13117 (3)
F8—C5—S1110.8 (3)C12—C13—H13123 (3)
C10—N9—C14122.8 (4)N9—C14—C13118.9 (4)
C10—N9—H9123 (3)N9—C14—H14114 (3)
C14—N9—H9114 (3)C13—C14—H14127 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N9—H9···O30.83 (4)2.24 (5)2.921 (5)140 (4)
N9—H9···O2i0.83 (4)2.29 (4)2.911 (5)132 (4)
C10—H10···O4i0.94 (4)2.46 (4)3.330 (5)153 (3)
C10—H10···O4ii0.94 (4)2.61 (4)3.199 (5)121 (3)
C11—H11···F7ii0.88 (4)2.69 (4)3.528 (5)159 (4)
C12—H12···O2iii0.89 (4)2.61 (5)3.389 (5)147 (4)
C12—H12···O3iv0.89 (4)2.59 (4)3.345 (5)142 (4)
C13—H13···O4v0.88 (4)2.60 (4)3.315 (5)138 (3)
C14—H14···O20.95 (4)2.40 (4)3.292 (5)156 (4)
Symmetry codes: (i) x+1/2, y+1/2, z+5/4; (ii) y+3/2, x+3/2, z+1/4; (iii) y+1/2, x+3/2, z+1/4; (iv) y+1, x+2, z+3/2; (v) x1/2, y+1/2, z+5/4.

Experimental details

Crystal data
Chemical formulaC5H6N+·CF3O3S
Mr229.18
Crystal system, space groupTetragonal, P43212
Temperature (K)110
a, c (Å)8.5265 (8), 24.388 (2)
V3)1773.0 (3)
Z8
Radiation typeMo Kα
µ (mm1)0.40
Crystal size (mm)0.45 × 0.20 × 0.10
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
11922, 1752, 1222
Rint0.057
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.059, 0.121, 1.03
No. of reflections1752
No. of parameters145
H-atom treatmentOnly H-atom coordinates refined
Δρmax, Δρmin (e Å3)0.38, 0.39
Absolute structureFlack (1983), 657 Friedel pairs
Absolute structure parameter0.08 (17)

Computer programs: Collect (Nonius, 1999), DENZO (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-III (Burnett & Johnson, 1996) and Mercury (Macrae et al., 2006).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N9—H9···O30.83 (4)2.24 (5)2.921 (5)140 (4)
N9—H9···O2i0.83 (4)2.29 (4)2.911 (5)132 (4)
C10—H10···O4i0.94 (4)2.46 (4)3.330 (5)153 (3)
C10—H10···O4ii0.94 (4)2.61 (4)3.199 (5)121 (3)
C11—H11···F7ii0.88 (4)2.69 (4)3.528 (5)159 (4)
C12—H12···O2iii0.89 (4)2.61 (5)3.389 (5)147 (4)
C12—H12···O3iv0.89 (4)2.59 (4)3.345 (5)142 (4)
C13—H13···O4v0.88 (4)2.60 (4)3.315 (5)138 (3)
C14—H14···O20.95 (4)2.40 (4)3.292 (5)156 (4)
Symmetry codes: (i) x+1/2, y+1/2, z+5/4; (ii) y+3/2, x+3/2, z+1/4; (iii) y+1/2, x+3/2, z+1/4; (iv) y+1, x+2, z+3/2; (v) x1/2, y+1/2, z+5/4.
 

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