organic compounds
3-Aminocarbonylpyridinium difluoroacetate at 123 K
aStrathclyde Institute of Pharmacy and Biomedical Sciences, The John Arbuthnott Building, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, Scotland, and bWestCHEM, Department of Pure & Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, Scotland
*Correspondence e-mail: j.bardin@strath.ac.uk
In the crystal of the title compound, C6H7N2O+·C2HF2O2−, the cation adopts a catemeric N—H⋯O hydrogen-bonded chain motif involving the carboxamide group, with two further N—H⋯O hydrogen bonds connecting the cations to adjacent difluoroacetate anions via the carboxamide and pyridinium N atoms. The carboxamide group of the nicotinamidium ion is twisted by 32.3 (6)° from the pyridine ring plane. A number of C—H⋯O and C—H⋯F interactions consolidate the packing.
Related literature
For nicotinamide, see: Wright & King (1954); Miwa et al. (1999); Hino et al. (2001). For nicotinamide solvates, co-crystals and salts, see: Bardin et al. (2009); Koman et al. (2003); Athimoolam & Natarajan (2007a,b); Fleischman et al. (2003); Berry et al. (2008). Identification was initially made using multi-sample foil transmission X-ray powder see: Florence et al. (2003).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON.
Supporting information
https://doi.org/10.1107/S1600536809043414/fl2272sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536809043414/fl2272Isup2.hkl
The novel structure reported here was discovered during a study of multicomponent crystal formation in organic compounds using a range of fluorinated acids. Identification of the novel phase was initially made using multi-sample foil transmission X-ray powder
(Florence et al., 2003) and a suitable single-crystal for was obtained by isothermal evaporation at 278 K of a of nicotinamide in DFAA.Aromatic H atoms bound to C were placed in idealized positions and in a riding mode, with C—H distance set to 0.95Å and Uiso equal to 1.2 times Ueq of the parent atom. All other H atoms were located by difference synthesis and then refined isotropically.
Nicotinamide (C6H6N2O, NA) is a member of the vitamin B group that includes pyridoxine, riboflavin and thiamine and its
was first determined in 1954 (Wright & King, 1954). Additional experimental investigations of charge density (Miwa et al.,1999) and (Hino et al., 2001) have also been reported although the crystal structures of other polymorphic forms have not been published. A number of multicomponent crystalline forms have been investigated including a trifluoroethanol solvate (Bardin et al., 2009), 3,5-dinitrosalicylate (Koman et al., 2003), 2R,3R-tartrate hydrate (Athimoolam & Natarajan, 2007a) and trifluoroacetate (Athimoolam & Natarajan, 2007b) salts. Co-crystals of NA have also been reported with drugs such as carbamazepine (Fleischman et al., 2003), salicylic acid and both the racemic and single (S(+)) forms of ibuprofen (Berry et al., 2008).The difluoroacetate (DFA-) salt reported here (Scheme 1) was discovered during a study of multicomponent crystal formation involving fluorinated solvents and a range of organic compounds. The ions in the NA+ DFA- salt crystallize in
P21/c with one NA+ cation and one DFA- anion in the (Fig.1). The internal C1—N1—C5 angle of the pyridinium ring in NA+ DFA- is 122.13 (9)°, in close agreement to the value reported in the NA+ TFA- salt (122.5 (4)°) but represents a significant increase over the the non-ionized form of NA (117.59 (7)°, Miwa et al., 1999). In the DFA- salt, as in the TFA- salt and NA structures, the carboxamide group is not coplanar with the pyridinium ring with the angle between the planes of these groups being 32.30 (6)° [16.3 (8)° and 22.16 (4)° for NA+ TFA- and NA respectively]. The packing in NA+ DFA- consists of hydrogen bonded chains of NA+ ions extending parallel to the a-axis via contact N2—H2N···O1 between the anti-oriented H atom of the NH2 group and the carbonyl O-atom, O1 (Fig. 2). Each cation forms an N—H···O hydrogen bond to O3 on a DFA- ion and this atom also accepts a second N—H···O hydrogen bond from a neighbouring cation in a parallel chain (Figure 3), that connect adjacent chains resulting in a two-dimensional sheet lying parallel to the ac plane. The remaining O-atom on the DFA- ion, O2, whilst not involved in any hydrogen bonds is involved in three C—H···O contacts to two DFA- ions and a cation. One further C—H···O contact is observed between O1 and C1—H1 on the pyridinium ring in a parallel chain of cations. C—H···F contacts are also observed (C3—H3···F1 and C4—H4···F2, see Table 2).For nicotinamide, see: Wright & King (1954); Miwa et al. (1999); Hino et al. (2001). For nicotinamide solvates, co-crystals and salts, see: Bardin et al. (2009); Koman et al. (2003); Athimoolam & Natarajan (2007a,b); Fleischman et al. (2003); Berry et al. (2008).
For related literature, see: Florence et al. (2003).
Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2009).Fig. 1. View of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level. | |
Fig. 2. The NA+ cations form chain motifs via N2—H2N···O1 interactions between carboxamide groups with two further N—H···O contacts formed to the DFA- anions. | |
Fig. 3. Chains of NA+ cations propagate down the a-axis with atom O3 connecting adjacent catemeric chains of cations (shown end on) via two N—H···O hydrogen bonds to N2—H3N on the carboxamide and N1—H1N on the pyridinium ring. |
C6H7N2O+·C2HF2O2− | F(000) = 448 |
Mr = 218.16 | Dx = 1.638 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 6311 reflections |
a = 4.9888 (2) Å | θ = 2.9–28.4° |
b = 25.6147 (12) Å | µ = 0.15 mm−1 |
c = 7.2006 (4) Å | T = 123 K |
β = 105.912 (2)° | Slab, colourless |
V = 884.88 (7) Å3 | 0.30 × 0.10 × 0.02 mm |
Z = 4 |
Bruker APEXII CCD diffractometer | 2201 independent reflections |
Radiation source: fine-focus sealed tube | 2087 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.015 |
φ and ω scans | θmax = 28.4°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2002) | h = −6→6 |
Tmin = 0.929, Tmax = 0.997 | k = −32→34 |
8921 measured reflections | l = −8→9 |
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)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.091 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0508P)2 + 0.323P] where P = (Fo2 + 2Fc2)/3 |
2201 reflections | (Δ/σ)max = 0.001 |
152 parameters | Δρmax = 0.41 e Å−3 |
1 restraint | Δρmin = −0.31 e Å−3 |
C6H7N2O+·C2HF2O2− | V = 884.88 (7) Å3 |
Mr = 218.16 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 4.9888 (2) Å | µ = 0.15 mm−1 |
b = 25.6147 (12) Å | T = 123 K |
c = 7.2006 (4) Å | 0.30 × 0.10 × 0.02 mm |
β = 105.912 (2)° |
Bruker APEXII CCD diffractometer | 2201 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2002) | 2087 reflections with I > 2σ(I) |
Tmin = 0.929, Tmax = 0.997 | Rint = 0.015 |
8921 measured reflections |
R[F2 > 2σ(F2)] = 0.034 | 1 restraint |
wR(F2) = 0.091 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.41 e Å−3 |
2201 reflections | Δρmin = −0.31 e Å−3 |
152 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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 | ||
O1 | 0.80371 (15) | 0.74427 (3) | 0.79966 (12) | 0.0214 (2) | |
N1 | 0.11038 (17) | 0.87200 (3) | 0.62567 (12) | 0.0159 (2) | |
N2 | 0.36157 (18) | 0.71520 (3) | 0.75584 (14) | 0.0186 (3) | |
C1 | 0.19020 (19) | 0.82177 (4) | 0.64341 (14) | 0.0146 (2) | |
C2 | 0.44978 (19) | 0.80807 (4) | 0.76136 (14) | 0.0139 (2) | |
C3 | 0.6222 (2) | 0.84727 (4) | 0.86318 (15) | 0.0176 (3) | |
C4 | 0.5320 (2) | 0.89865 (4) | 0.84480 (15) | 0.0199 (3) | |
C5 | 0.2730 (2) | 0.91037 (4) | 0.72202 (15) | 0.0187 (3) | |
C6 | 0.5522 (2) | 0.75269 (4) | 0.77430 (14) | 0.0149 (2) | |
F1 | 0.12172 (14) | 0.59643 (3) | 0.66362 (11) | 0.0300 (2) | |
F2 | 0.27896 (15) | 0.52181 (3) | 0.59164 (10) | 0.0292 (2) | |
O2 | 0.73632 (16) | 0.53207 (3) | 0.90515 (13) | 0.0238 (3) | |
O3 | 0.61539 (15) | 0.61630 (3) | 0.89351 (11) | 0.0201 (2) | |
C7 | 0.56993 (19) | 0.56809 (4) | 0.85520 (14) | 0.0147 (2) | |
C8 | 0.2715 (2) | 0.55331 (4) | 0.74290 (15) | 0.0177 (3) | |
H1 | 0.06810 | 0.79550 | 0.57480 | 0.0180* | |
H1N | −0.063 (2) | 0.8784 (7) | 0.543 (2) | 0.045 (5)* | |
H2N | 0.185 (3) | 0.7234 (6) | 0.750 (2) | 0.026 (4)* | |
H3 | 0.80110 | 0.83880 | 0.94500 | 0.0210* | |
H3N | 0.422 (3) | 0.6835 (6) | 0.773 (2) | 0.027 (4)* | |
H4 | 0.64680 | 0.92550 | 0.91570 | 0.0240* | |
H5 | 0.21060 | 0.94550 | 0.70600 | 0.0220* | |
H6 | 0.171 (3) | 0.5363 (5) | 0.822 (2) | 0.017 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0136 (4) | 0.0203 (4) | 0.0305 (4) | 0.0040 (3) | 0.0065 (3) | 0.0053 (3) |
N1 | 0.0135 (4) | 0.0148 (4) | 0.0183 (4) | 0.0022 (3) | 0.0027 (3) | 0.0026 (3) |
N2 | 0.0156 (4) | 0.0124 (4) | 0.0281 (5) | 0.0020 (3) | 0.0066 (3) | 0.0021 (3) |
C1 | 0.0130 (4) | 0.0137 (4) | 0.0168 (4) | −0.0002 (3) | 0.0034 (3) | 0.0009 (3) |
C2 | 0.0132 (4) | 0.0132 (4) | 0.0154 (4) | 0.0012 (3) | 0.0042 (3) | 0.0020 (3) |
C3 | 0.0140 (4) | 0.0181 (5) | 0.0186 (4) | 0.0002 (3) | 0.0011 (3) | 0.0005 (3) |
C4 | 0.0196 (5) | 0.0156 (5) | 0.0223 (5) | −0.0022 (4) | 0.0023 (4) | −0.0023 (4) |
C5 | 0.0202 (5) | 0.0139 (4) | 0.0218 (5) | 0.0017 (3) | 0.0054 (4) | 0.0009 (3) |
C6 | 0.0144 (4) | 0.0152 (4) | 0.0149 (4) | 0.0025 (3) | 0.0039 (3) | 0.0021 (3) |
F1 | 0.0183 (3) | 0.0226 (3) | 0.0402 (4) | 0.0048 (2) | −0.0072 (3) | 0.0045 (3) |
F2 | 0.0318 (4) | 0.0254 (3) | 0.0267 (4) | −0.0055 (3) | 0.0020 (3) | −0.0094 (3) |
O2 | 0.0151 (4) | 0.0154 (4) | 0.0377 (5) | 0.0025 (3) | 0.0019 (3) | 0.0020 (3) |
O3 | 0.0158 (3) | 0.0128 (3) | 0.0276 (4) | −0.0002 (3) | −0.0007 (3) | −0.0019 (3) |
C7 | 0.0122 (4) | 0.0140 (4) | 0.0175 (4) | −0.0006 (3) | 0.0036 (3) | 0.0005 (3) |
C8 | 0.0146 (4) | 0.0146 (4) | 0.0216 (5) | −0.0006 (3) | 0.0011 (4) | 0.0003 (4) |
F1—C8 | 1.3676 (13) | C1—C2 | 1.3851 (14) |
F2—C8 | 1.3642 (13) | C2—C6 | 1.5020 (14) |
O1—C6 | 1.2364 (13) | C2—C3 | 1.3928 (14) |
O2—C7 | 1.2272 (13) | C3—C4 | 1.3854 (15) |
O3—C7 | 1.2721 (13) | C4—C5 | 1.3838 (15) |
N1—C1 | 1.3425 (13) | C1—H1 | 0.9500 |
N1—C5 | 1.3405 (13) | C3—H3 | 0.9500 |
N2—C6 | 1.3323 (13) | C4—H4 | 0.9500 |
N1—H1N | 0.920 (12) | C5—H5 | 0.9500 |
N2—H2N | 0.895 (16) | C7—C8 | 1.5342 (14) |
N2—H3N | 0.863 (15) | C8—H6 | 0.960 (14) |
F1···C3i | 3.1645 (13) | C1···O1xi | 3.1802 (13) |
F1···O3 | 2.6133 (11) | C1···N2iii | 3.2748 (14) |
F1···C4i | 3.1997 (13) | C1···O1i | 3.1763 (13) |
F2···C4ii | 3.2885 (13) | C1···O3i | 3.3389 (13) |
F2···C4iii | 3.1834 (13) | C3···N1vii | 3.3972 (14) |
F2···F2iv | 2.9535 (11) | C3···F1vi | 3.1645 (13) |
F2···F2v | 3.0741 (11) | C4···F2x | 3.1834 (13) |
F2···O2 | 2.7472 (11) | C4···O3iii | 3.4089 (13) |
F2···C5iii | 3.1716 (13) | C4···F2xii | 3.2885 (13) |
F1···H4i | 2.6100 | C4···F1vi | 3.1997 (13) |
F1···H3i | 2.5300 | C5···O2i | 3.3464 (14) |
F1···H3N | 2.682 (15) | C5···C8iii | 3.5712 (15) |
F2···H4iii | 2.8400 | C5···F2x | 3.1716 (13) |
F2···H5iii | 2.8300 | C5···O3iii | 3.3459 (13) |
F2···H4ii | 2.5000 | C5···C7iii | 3.4089 (14) |
O1···C1vi | 3.1763 (13) | C5···O2xii | 3.2458 (13) |
O1···C1vii | 3.1802 (13) | C7···C5x | 3.4089 (14) |
O1···N2vii | 2.9801 (12) | C7···N1vi | 3.2463 (13) |
O2···C8vii | 3.2403 (14) | C8···C5x | 3.5712 (15) |
O2···F2 | 2.7472 (11) | C8···O2ix | 3.3558 (13) |
O2···O2viii | 3.0848 (12) | C8···O2xi | 3.2403 (14) |
O2···C8ix | 3.3558 (13) | C1···H2Niii | 3.054 (14) |
O2···C5ii | 3.2458 (13) | C1···H2N | 2.636 (15) |
O2···N1vi | 3.2275 (12) | C7···H3N | 3.065 (15) |
O2···C5vi | 3.3464 (14) | C7···H1Nvi | 2.388 (14) |
O3···F1 | 2.6133 (11) | H1···O1i | 2.3000 |
O3···C5x | 3.3459 (13) | H1···H2N | 2.2200 |
O3···N2 | 2.8836 (11) | H1···N2 | 2.6500 |
O3···N1vi | 2.5921 (12) | H1···O1xi | 2.6900 |
O3···C1vi | 3.3389 (13) | H1N···O3i | 1.675 (12) |
O3···C4x | 3.4089 (13) | H1N···C7i | 2.388 (14) |
O1···H2Nvii | 2.099 (15) | H1N···O2i | 2.589 (17) |
O1···H3 | 2.6400 | H2N···C1x | 3.054 (14) |
O1···H1vi | 2.3000 | H2N···O1xi | 2.099 (15) |
O1···H1vii | 2.6900 | H2N···C1 | 2.636 (15) |
O2···H6ix | 2.577 (13) | H2N···H1 | 2.2200 |
O2···H1Nvi | 2.589 (17) | H3···O1 | 2.6400 |
O2···H6vii | 2.405 (15) | H3···F1vi | 2.5300 |
O2···H5vi | 2.7900 | H3N···F1 | 2.682 (15) |
O2···H5ii | 2.4000 | H3N···O3 | 2.046 (15) |
O3···H3N | 2.046 (15) | H3N···C7 | 3.065 (15) |
O3···H1Nvi | 1.675 (12) | H4···F2x | 2.8400 |
N1···C3xi | 3.3972 (14) | H4···F2xii | 2.5000 |
N1···C7i | 3.2463 (13) | H4···F1vi | 2.6100 |
N1···O2i | 3.2275 (12) | H5···F2x | 2.8300 |
N1···O3i | 2.5921 (12) | H5···O2i | 2.7900 |
N2···O3 | 2.8836 (11) | H5···O2xii | 2.4000 |
N2···O1xi | 2.9801 (12) | H6···O2xi | 2.405 (15) |
N2···C1x | 3.2748 (14) | H6···O2ix | 2.577 (13) |
N2···H1 | 2.6500 | ||
C1—N1—C5 | 122.13 (9) | C2—C1—H1 | 120.00 |
C1—N1—H1N | 115.7 (11) | C2—C3—H3 | 120.00 |
C5—N1—H1N | 122.2 (11) | C4—C3—H3 | 120.00 |
C6—N2—H2N | 120.1 (10) | C3—C4—H4 | 120.00 |
H2N—N2—H3N | 121.9 (14) | C5—C4—H4 | 120.00 |
C6—N2—H3N | 116.9 (10) | N1—C5—H5 | 120.00 |
N1—C1—C2 | 120.28 (9) | C4—C5—H5 | 120.00 |
C1—C2—C6 | 121.49 (9) | O2—C7—O3 | 126.89 (10) |
C1—C2—C3 | 118.61 (9) | O2—C7—C8 | 116.72 (9) |
C3—C2—C6 | 119.85 (9) | O3—C7—C8 | 116.32 (9) |
C2—C3—C4 | 119.80 (10) | F1—C8—F2 | 106.01 (8) |
C3—C4—C5 | 119.28 (10) | F1—C8—C7 | 111.16 (8) |
N1—C5—C4 | 119.88 (9) | F2—C8—C7 | 109.38 (8) |
O1—C6—C2 | 119.22 (9) | F1—C8—H6 | 107.4 (9) |
N2—C6—C2 | 116.95 (9) | F2—C8—H6 | 109.8 (8) |
O1—C6—N2 | 123.83 (10) | C7—C8—H6 | 112.9 (9) |
N1—C1—H1 | 120.00 | ||
C5—N1—C1—C2 | −1.18 (15) | C3—C2—C6—O1 | −30.80 (14) |
C1—N1—C5—C4 | −0.15 (15) | C3—C2—C6—N2 | 149.70 (10) |
N1—C1—C2—C3 | 1.24 (15) | C2—C3—C4—C5 | −1.27 (15) |
N1—C1—C2—C6 | −176.03 (9) | C3—C4—C5—N1 | 1.38 (15) |
C1—C2—C3—C4 | −0.02 (15) | O2—C7—C8—F1 | −168.25 (9) |
C6—C2—C3—C4 | 177.30 (9) | O2—C7—C8—F2 | −51.53 (12) |
C1—C2—C6—O1 | 146.44 (10) | O3—C7—C8—F1 | 14.57 (12) |
C1—C2—C6—N2 | −33.06 (14) | O3—C7—C8—F2 | 131.29 (9) |
Symmetry codes: (i) x−1, −y+3/2, z−1/2; (ii) −x+1, y−1/2, −z+3/2; (iii) x, −y+3/2, z−1/2; (iv) −x, −y+1, −z+1; (v) −x+1, −y+1, −z+1; (vi) x+1, −y+3/2, z+1/2; (vii) x+1, y, z; (viii) −x+2, −y+1, −z+2; (ix) −x+1, −y+1, −z+2; (x) x, −y+3/2, z+1/2; (xi) x−1, y, z; (xii) −x+1, y+1/2, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O2i | 0.920 (12) | 2.589 (17) | 3.2275 (12) | 127.0 (13) |
N1—H1N···O3i | 0.920 (12) | 1.675 (12) | 2.5921 (12) | 174.3 (17) |
N2—H2N···O1xi | 0.895 (16) | 2.099 (15) | 2.9801 (12) | 167.9 (13) |
N2—H3N···O3 | 0.863 (15) | 2.046 (15) | 2.8836 (11) | 163.2 (13) |
C1—H1···O1i | 0.95 | 2.30 | 3.1763 (13) | 154 |
C3—H3···F1vi | 0.95 | 2.53 | 3.1645 (13) | 124 |
C4—H4···F2xii | 0.95 | 2.50 | 3.2885 (13) | 141 |
C5—H5···O2xii | 0.95 | 2.40 | 3.2458 (13) | 149 |
C8—H6···O2xi | 0.960 (14) | 2.405 (15) | 3.2403 (14) | 145.2 (11) |
C8—H6···O2ix | 0.960 (14) | 2.577 (13) | 3.3558 (13) | 138.3 (12) |
Symmetry codes: (i) x−1, −y+3/2, z−1/2; (vi) x+1, −y+3/2, z+1/2; (ix) −x+1, −y+1, −z+2; (xi) x−1, y, z; (xii) −x+1, y+1/2, −z+3/2. |
Experimental details
Crystal data | |
Chemical formula | C6H7N2O+·C2HF2O2− |
Mr | 218.16 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 123 |
a, b, c (Å) | 4.9888 (2), 25.6147 (12), 7.2006 (4) |
β (°) | 105.912 (2) |
V (Å3) | 884.88 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.15 |
Crystal size (mm) | 0.30 × 0.10 × 0.02 |
Data collection | |
Diffractometer | Bruker APEXII CCD |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2002) |
Tmin, Tmax | 0.929, 0.997 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8921, 2201, 2087 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.669 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.091, 1.05 |
No. of reflections | 2201 |
No. of parameters | 152 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.41, −0.31 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and Mercury (Macrae et al., 2006), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O2i | 0.920 (12) | 2.589 (17) | 3.2275 (12) | 127.0 (13) |
N1—H1N···O3i | 0.920 (12) | 1.675 (12) | 2.5921 (12) | 174.3 (17) |
N2—H2N···O1ii | 0.895 (16) | 2.099 (15) | 2.9801 (12) | 167.9 (13) |
N2—H3N···O3 | 0.863 (15) | 2.046 (15) | 2.8836 (11) | 163.2 (13) |
C1—H1···O1i | 0.9500 | 2.3000 | 3.1763 (13) | 154.00 |
C3—H3···F1iii | 0.9500 | 2.5300 | 3.1645 (13) | 124.00 |
C4—H4···F2iv | 0.9500 | 2.5000 | 3.2885 (13) | 141.00 |
C5—H5···O2iv | 0.9500 | 2.4000 | 3.2458 (13) | 149.00 |
C8—H6···O2ii | 0.960 (14) | 2.405 (15) | 3.2403 (14) | 145.2 (11) |
C8—H6···O2v | 0.960 (14) | 2.577 (13) | 3.3558 (13) | 138.3 (12) |
Symmetry codes: (i) x−1, −y+3/2, z−1/2; (ii) x−1, y, z; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+2. |
Acknowledgements
The authors thank the University of Strathclyde for funding JB, the Basic Technology programme of the UK Research Councils for project funding under the Control and Prediction of the Organic Solid State (www.cposs.org.uk) and the Glasgow Centre for Physical Organic Chemistry for access to single-crystal diffraction facilities.
References
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Nicotinamide (C6H6N2O, NA) is a member of the vitamin B group that includes pyridoxine, riboflavin and thiamine and its crystal structure was first determined in 1954 (Wright & King, 1954). Additional experimental investigations of charge density (Miwa et al.,1999) and polymorphism (Hino et al., 2001) have also been reported although the crystal structures of other polymorphic forms have not been published. A number of multicomponent crystalline forms have been investigated including a trifluoroethanol solvate (Bardin et al., 2009), 3,5-dinitrosalicylate (Koman et al., 2003), 2R,3R-tartrate hydrate (Athimoolam & Natarajan, 2007a) and trifluoroacetate (Athimoolam & Natarajan, 2007b) salts. Co-crystals of NA have also been reported with drugs such as carbamazepine (Fleischman et al., 2003), salicylic acid and both the racemic and single enantiomer (S(+)) forms of ibuprofen (Berry et al., 2008).
The difluoroacetate (DFA-) salt reported here (Scheme 1) was discovered during a study of multicomponent crystal formation involving fluorinated solvents and a range of organic compounds. The ions in the NA+ DFA- salt crystallize in space group P21/c with one NA+ cation and one DFA- anion in the asymmetric unit (Fig.1). The internal C1—N1—C5 angle of the pyridinium ring in NA+ DFA- is 122.13 (9)°, in close agreement to the value reported in the NA+ TFA- salt (122.5 (4)°) but represents a significant increase over the the non-ionized form of NA (117.59 (7)°, Miwa et al., 1999). In the DFA- salt, as in the TFA- salt and NA structures, the carboxamide group is not coplanar with the pyridinium ring with the angle between the planes of these groups being 32.30 (6)° [16.3 (8)° and 22.16 (4)° for NA+ TFA- and NA respectively]. The packing in NA+ DFA- consists of hydrogen bonded chains of NA+ ions extending parallel to the a-axis via contact N2—H2N···O1 between the anti-oriented H atom of the NH2 group and the carbonyl O-atom, O1 (Fig. 2). Each cation forms an N—H···O hydrogen bond to O3 on a DFA- ion and this atom also accepts a second N—H···O hydrogen bond from a neighbouring cation in a parallel chain (Figure 3), that connect adjacent chains resulting in a two-dimensional sheet lying parallel to the ac plane. The remaining O-atom on the DFA- ion, O2, whilst not involved in any hydrogen bonds is involved in three C—H···O contacts to two DFA- ions and a cation. One further C—H···O contact is observed between O1 and C1—H1 on the pyridinium ring in a parallel chain of cations. C—H···F contacts are also observed (C3—H3···F1 and C4—H4···F2, see Table 2).