Nicotinium trifluoro­acetate

Athimoolam, S.; Natarajan, S.

doi:10.1107/S1600536807019216

Nicotinium trifluoroacetate

In the title compound, C₆H₆NO₂⁺·C₂O₂F₃⁻, the carboxyl group is twisted from the planar pyridine ring by an angle of 5.2 (6)°. The protonated cations and the anions are linked through N—H

O and O—H

O hydrogen bonds, forming a C₂¹(8) chain motif with two-dimensional lamellar sheets parallel to (010). These sheets are separated by a distance of 3.092 (4) Å and there are no hydrogen bonds between them. The F atoms are each disordered unequally over two positions.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807019216/sj2293sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807019216/sj2293Isup2.hkl Contains datablock I

CCDC reference: 647684

checkCIF report

Key indicators

Single-crystal X-ray study
T = 293 K
Mean (C-C) = 0.005 Å
Disorder in main residue
R factor = 0.053
wR factor = 0.087
Data-to-parameter ratio = 9.7

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT242_ALERT_2_A Check Low       Ueq as Compared to Neighbors for        C22

Author Response: As fluorine atoms are in disordered, the thermal parameters of these atoms are high. Hence, the comparision with the C22 atom (neighbour) shows low Ueq value.


Alert level C
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         48 Perc.
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.98
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       9.68
PLAT213_ALERT_2_C Atom F2      has ADP max/min Ratio .............       3.30 oblat
PLAT213_ALERT_2_C Atom F2'     has ADP max/min Ratio .............       3.90 prola
PLAT220_ALERT_2_C Large Non-Solvent    F     Ueq(max)/Ueq(min) ...       2.72 Ratio
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C21

Author Response: As fluorine atoms are in disordered, the thermal parameters of these atoms are high. Hence, the comparision with the C22 atom (neighbour) shows low Ueq value.

PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.38
PLAT301_ALERT_3_C Main Residue  Disorder .........................      16.00 Perc.
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   1 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
  11 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   6 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

Comment top

Nicotinic acid (pyridine-3-carboxylic acid) is a B vitamin known as niacin, and has a variety of pharmacological properties as detailed in our previous publications (Athimoolam & Rajaram, 2005a,b). As vitamin B is one of the important biological compounds in many fields such as the pharmaceutical industry, it is very useful to study ionic crystals of the vitamin in inorganic/organic acid environment. The planar nicotinic acid ligand has potential sites for hydrogen-bonding interactions, viz., the pyridine N atom, and the carboxylic O atoms. These effective hydrogen-bonding sites make this molecule to act as an important supramolecular organic synthon. The present work is part of our ongoing work on vitamin-inorganic/organic complexes to study the different hydrogen-bond motifs.

The asymmetric unit of the title compound (I) contains a nicotinium cation and a trifluoroacetate anion (Fig 1). The fluorine atoms of the trifluoroacetate are observed to have 'rotational disorder' about the C—C bond. Deprotonation of the anion and protonation of the cation are confirmed by the C—N and C—O bond distances (Table 1). Characteristic features of the protonated nicotinium structure are the twisting of the carboxylic acid plane out of the pyridine ring plane and a significant widening of the C—N—C angle in the pyridine ring (>120°) (Cambridge Structural Database; Version 5.28 of 2008; Allen, 2002). Both these features are observed in (I) (Table 1), with the angle of twisting between the carboxylic acid and pyridine ring planes being 5.2 (6)°. The deviations of the atoms O1A and O1B from the plane of the pyridine ring are observed to be -0.112 (5) and 0.090 (5) Å, respectively.

Anions link cations through N—H···O and O—H···O hydrogen bonds forming a C₂¹(8) chain motif (Etter et al., 1990). Normally, nicotinium cations are linked together interactions leading to a sheet like structure (Athimoolam & Natarajan, 2006). But in (I), cations and anions are linked leading to a sheet like structure parallel to the ac plane of the crystal (Fig. 2; Table 2). These two-dimensional hydrogen-bonded sheets are separated by a distance of 3.092 (4) Å. There are no hydrogen bonding interactions between these sheets.

Related literature top

For related literature on hydrogen-bond motifs, see: Etter et al. (1990). For values of bond lengths and angles, see: Allen (2002). For information on the pharmacological properties of nicotinic acid, see: Athimoolam & Rajaram (2005a,b). For a related structure, see: Athimoolam & Natarajan (2006).

Experimental top

The title compound (I) was crystallized from an aqueous mixture containing nicotinic acid and trifluoroacetic acid, in the stochiometric ratio of 1:1, by the technique of slow evaporation.

Structure description top

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXTL/PC (Bruker, 2000); program(s) used to refine structure: SHELXTL/PC; molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL/PC.

Figures top

	Fig. 1. The molecular structure of (I), shwoing the atom-numbering scheme and 50% probability displacement ellipsoids. Hydrogen bonds are shown as dashed lines. Only the major component of the disordered F atoms are shown.
	Fig. 2. Packing diagram of the molecules viewed down the c-axis. Minor components of the disordered F atoms are omitted for clarity. H-bonds are shown as dashed lines.

Nicotinium trifluoroacetate top

Crystal data top

C₆H₆NO₂⁺·C₂O₂F₃⁻	Z = 2
M_r = 237.14	F(000) = 240
Triclinic, P1	D_x = 1.653 Mg m⁻³ D_m = 1.65 (1) Mg m⁻³ D_m measured by flotation using a mixture of xylene and bromoform
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.1981 (7) Å	Cell parameters from 25 reflections
b = 8.6292 (8) Å	θ = 9.5–15.1°
c = 8.8580 (6) Å	µ = 0.17 mm⁻¹
α = 62.036 (11)°	T = 293 K
β = 86.867 (14)°	Block, colourless
γ = 61.818 (9)°	0.22 × 0.19 × 0.15 mm
V = 476.53 (11) Å³

Data collection top

Nonius MACH3 sealed tube diffractometer	809 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.016
Graphite monochromator	θ_max = 25.0°, θ_min = 2.7°
ω–2θ scans	h = −1→9
Absorption correction: ψ scan (North et al., 1968)	k = −9→10
T_min = 0.963, T_max = 0.995	l = −10→10
2060 measured reflections	3 standard reflections every 60 min
1674 independent reflections	intensity decay: none

Refinement top

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)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.088	H-atom parameters constrained
S = 0.96	w = 1/[σ²(F_o²) + (0.0354P)² + ] where P = (F_o² + 2F_c²)/3
1674 reflections	(Δ/σ)_max < 0.001
173 parameters	Δρ_max = 0.15 e Å⁻³
9 restraints	Δρ_min = −0.16 e Å⁻³

Crystal data top

C₆H₆NO₂⁺·C₂O₂F₃⁻	γ = 61.818 (9)°
M_r = 237.14	V = 476.53 (11) Å³
Triclinic, P1	Z = 2
a = 8.1981 (7) Å	Mo Kα radiation
b = 8.6292 (8) Å	µ = 0.17 mm⁻¹
c = 8.8580 (6) Å	T = 293 K
α = 62.036 (11)°	0.22 × 0.19 × 0.15 mm
β = 86.867 (14)°

Data collection top

Nonius MACH3 sealed tube diffractometer	809 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.016
T_min = 0.963, T_max = 0.995	3 standard reflections every 60 min
2060 measured reflections	intensity decay: none
1674 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.053	9 restraints
wR(F²) = 0.088	H-atom parameters constrained
S = 0.96	Δρ_max = 0.15 e Å⁻³
1674 reflections	Δρ_min = −0.16 e Å⁻³
173 parameters

Special details top

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
N1	−0.0844 (3)	0.2751 (3)	−0.0477 (3)	0.0451 (6)
H1	−0.1676	0.2813	0.0163	0.054*
C2	0.0696 (4)	0.2693 (3)	0.0028 (3)	0.0422 (8)
H2	0.0836	0.2719	0.1050	0.051*
C3	0.2086 (4)	0.2595 (4)	−0.0934 (4)	0.0460 (8)
C31	0.3802 (5)	0.2516 (5)	−0.0425 (4)	0.0503 (8)
O1A	0.5100 (3)	0.2306 (3)	−0.1179 (3)	0.0652 (7)
O1B	0.3770 (3)	0.2727 (4)	0.0958 (3)	0.0719 (7)
H1B	0.4762	0.2643	0.1226	0.108*
C4	0.1767 (4)	0.2599 (4)	−0.2455 (4)	0.0582 (9)
H4	0.2633	0.2589	−0.3179	0.070*
C5	0.0163 (4)	0.2618 (4)	−0.2902 (4)	0.0531 (9)
H5	−0.0009	0.2561	−0.3900	0.064*
C6	−0.1164 (4)	0.2718 (4)	−0.1907 (4)	0.0587 (9)
H6	−0.2256	0.2763	−0.2220	0.070*
O21	0.8754 (3)	0.2793 (3)	0.3340 (3)	0.0650 (7)
O22	0.6891 (3)	0.2585 (3)	0.1815 (3)	0.0633 (6)
C21	0.7513 (4)	0.2472 (4)	0.3171 (4)	0.0477 (8)
C22	0.6485 (6)	0.1903 (8)	0.4611 (6)	0.0757 (12)
F1	0.7186 (18)	0.157 (2)	0.6044 (12)	0.172 (6)	0.57
F2	0.4680 (8)	0.2901 (13)	0.4224 (12)	0.094 (3)	0.57
F3	0.6864 (17)	−0.0022 (13)	0.5179 (17)	0.151 (6)	0.57
F1'	0.7359 (19)	0.1224 (14)	0.6155 (11)	0.085 (4)	0.43
F2'	0.4762 (15)	0.316 (2)	0.4358 (17)	0.231 (10)	0.43
F3'	0.665 (2)	0.012 (2)	0.499 (2)	0.134 (7)	0.43

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0231 (14)	0.0605 (16)	0.0562 (16)	−0.0302 (13)	0.0134 (12)	−0.0239 (13)
C2	0.046 (2)	0.0277 (16)	0.0353 (16)	−0.0162 (16)	0.0041 (16)	−0.0059 (14)
C3	0.045 (2)	0.055 (2)	0.0469 (18)	−0.0248 (17)	0.0243 (16)	−0.0340 (16)
C31	0.048 (2)	0.067 (2)	0.054 (2)	−0.0385 (18)	0.0198 (18)	−0.0347 (18)
O1A	0.0443 (13)	0.0908 (16)	0.0751 (15)	−0.0427 (13)	0.0229 (12)	−0.0445 (13)
O1B	0.0434 (15)	0.1169 (19)	0.0796 (16)	−0.0543 (15)	0.0182 (13)	−0.0530 (15)
C4	0.050 (2)	0.065 (2)	0.063 (2)	−0.0296 (19)	0.0355 (18)	−0.0353 (19)
C5	0.0347 (19)	0.071 (2)	0.058 (2)	−0.0268 (18)	0.0097 (18)	−0.0348 (18)
C6	0.052 (2)	0.067 (2)	0.0424 (19)	−0.0227 (19)	0.0014 (18)	−0.0232 (18)
O21	0.0561 (15)	0.0838 (16)	0.0779 (16)	−0.0486 (13)	0.0148 (12)	−0.0434 (13)
O22	0.0612 (14)	0.0983 (16)	0.0577 (13)	−0.0576 (13)	0.0292 (12)	−0.0428 (13)
C21	0.040 (2)	0.069 (2)	0.0364 (19)	−0.0394 (19)	0.0130 (16)	−0.0166 (17)
C22	0.060 (3)	0.133 (4)	0.104 (3)	−0.060 (3)	0.037 (3)	−0.098 (3)
F1	0.185 (13)	0.368 (15)	0.103 (7)	−0.201 (12)	0.079 (7)	−0.159 (8)
F2	0.032 (4)	0.126 (6)	0.106 (6)	−0.031 (4)	0.043 (4)	−0.057 (5)
F3	0.098 (7)	0.103 (6)	0.168 (10)	−0.044 (6)	0.041 (6)	−0.017 (7)
F1'	0.089 (9)	0.087 (5)	0.042 (5)	−0.033 (5)	0.004 (5)	−0.018 (4)
F2'	0.092 (9)	0.191 (12)	0.073 (8)	0.069 (7)	0.038 (7)	0.026 (7)
F3'	0.188 (16)	0.188 (12)	0.128 (10)	−0.153 (14)	0.050 (9)	−0.094 (10)

Geometric parameters (Å, º) top

N1—C6	1.324 (3)	C5—C6	1.359 (4)
N1—C2	1.334 (3)	C5—H5	0.9300
N1—H1	0.8600	C6—H6	0.9300
C2—C3	1.379 (3)	O21—C21	1.206 (3)
C2—H2	0.9300	O22—C21	1.273 (3)
C3—C4	1.385 (4)	C21—C22	1.505 (4)
C3—C31	1.462 (4)	C22—F2'	1.256 (10)
C31—O1A	1.211 (3)	C22—F1	1.266 (9)
C31—O1B	1.317 (3)	C22—F2	1.274 (7)
O1B—H1B	0.8200	C22—F1'	1.299 (10)
C4—C5	1.384 (4)	C22—F3'	1.352 (11)
C4—H4	0.9300	C22—F3	1.362 (9)

C6—N1—C2	123.6 (3)	O21—C21—O22	126.4 (3)
C6—N1—H1	118.2	O21—C21—C22	121.7 (3)
C2—N1—H1	118.2	O22—C21—C22	111.9 (3)
N1—C2—C3	121.3 (3)	F2'—C22—F1	102.8 (9)
N1—C2—H2	119.3	F1—C22—F2	113.9 (8)
C3—C2—H2	119.3	F2'—C22—F1'	109.9 (10)
C2—C3—C4	116.2 (3)	F2—C22—F1'	119.3 (8)
C2—C3—C31	123.2 (3)	F2'—C22—F3'	108.3 (11)
C4—C3—C31	120.6 (3)	F1—C22—F3'	104.7 (10)
O1A—C31—O1B	123.3 (3)	F2—C22—F3'	95.3 (8)
O1A—C31—C3	124.8 (3)	F1'—C22—F3'	95.3 (9)
O1B—C31—C3	111.9 (3)	F2'—C22—F3	113.9 (10)
C31—O1B—H1B	109.5	F1—C22—F3	97.2 (9)
C5—C4—C3	120.2 (3)	F2—C22—F3	101.7 (7)
C5—C4—H4	119.9	F1'—C22—F3	87.6 (8)
C3—C4—H4	119.9	F2'—C22—C21	117.8 (7)
C6—C5—C4	121.1 (3)	F1—C22—C21	114.0 (7)
C6—C5—H5	119.4	F2—C22—C21	117.8 (5)
C4—C5—H5	119.4	F1'—C22—C21	114.7 (7)
N1—C6—C5	117.5 (3)	F3'—C22—C21	108.4 (8)
N1—C6—H6	121.2	F3—C22—C21	109.2 (6)
C5—C6—H6	121.2

C6—N1—C2—C3	0.1 (4)	O21—C21—C22—F2'	112.8 (11)
N1—C2—C3—C4	1.1 (4)	O22—C21—C22—F2'	−66.3 (11)
N1—C2—C3—C31	−179.6 (3)	O21—C21—C22—F1	−7.8 (9)
C2—C3—C31—O1A	175.3 (3)	O22—C21—C22—F1	173.1 (7)
C4—C3—C31—O1A	−5.5 (5)	O21—C21—C22—F2	129.5 (6)
C2—C3—C31—O1B	−5.5 (4)	O22—C21—C22—F2	−49.6 (7)
C4—C3—C31—O1B	173.8 (3)	O21—C21—C22—F1'	−18.9 (8)
C2—C3—C4—C5	−2.5 (4)	O22—C21—C22—F1'	162.0 (6)
C31—C3—C4—C5	178.2 (3)	O21—C21—C22—F3'	−123.9 (7)
C3—C4—C5—C6	2.8 (5)	O22—C21—C22—F3'	57.0 (8)
C2—N1—C6—C5	0.1 (4)	O21—C21—C22—F3	−115.2 (7)
C4—C5—C6—N1	−1.5 (4)	O22—C21—C22—F3	65.6 (7)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O22ⁱ	0.86	1.82	2.675 (3)	170
O1B—H1B···O22	0.82	1.82	2.639 (3)	177

Symmetry code: (i) x−1, y, z.

Experimental details

Crystal data
Chemical formula	C₆H₆NO₂⁺·C₂O₂F₃⁻
M_r	237.14
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	8.1981 (7), 8.6292 (8), 8.8580 (6)
α, β, γ (°)	62.036 (11), 86.867 (14), 61.818 (9)
V (Å³)	476.53 (11)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.17
Crystal size (mm)	0.22 × 0.19 × 0.15

Data collection
Diffractometer	Nonius MACH3 sealed tube
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.963, 0.995
No. of measured, independent and observed [I > 2σ(I)] reflections	2060, 1674, 809
R_int	0.016
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.088, 0.96
No. of reflections	1674
No. of parameters	173
No. of restraints	9
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.15, −0.16

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXTL/PC (Bruker, 2000), SHELXTL/PC, ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003).