organic compounds
Intra- and intermolecular proton transfer in 2,6-diaminopyridinium 4-hydroxypyridin-1-ium-2,6-dicarboxylate
aInstitut für Organische Chemie und Chemische Biologie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main, Germany, and bInstitut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main, Germany
*Correspondence e-mail: bolte@chemie.uni-frankfurt.de
Chelidamic acid (4-hydroxypyridine-2,6-dicarboxylic acid) and 2,6-diaminopyridine react to form the title salt, C5H8N3+·C7H4NO5−; there are two formula units in the The pyridine N atom of 2,6-diaminopyridine is protonated whereas chelidamic acid is deprotonated at both carboxylate groups but protonated at the N atom; the reaction involves intra- and intermolecular proton transfer. In the crystal, each 2,6-diaminopyridinium cation participates in five strong N—H⋯O hydrogen bonds (including one bifurcated hydrogen bond). The also features strong O—H⋯O hydrogen bonds between the chelidamate anions, leading to chains along the a axis.
Related literature
For chelidamic acid, see: Tutughamiarso et al. (2012). For chelidamic acid monohydrate, see: Hall et al. (2000). For interaction of chelidamic acid with heavy metal ions, see: Norkus et al. (2003). For supermolecular structures, see: Aakeröy et al. (2005); Brunsveld et al. (2001); Prins et al. (2001); Schmid & Mann (1954). For a description of the Cambridge Structural Database, see: Allen (2002).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: X-AREA (Stoe & Cie, 2001); cell X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008) and XP (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip (2010).
Supporting information
https://doi.org/10.1107/S1600536812037580/ng5291sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812037580/ng5291Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812037580/ng5291Isup3.cml
Chelidamic acid and 2,6-diaminopyridine are commercially available. Chelidamic acid was utilized without purification while 2,6-diaminopyridine had to be sublimed before use. A small amount of each compound was dissolved separately in approximately 15 drops of dimethyl sulfoxide (DMSO) before they were combined in a flask and set aside at room temperature. From the green-yellow mixture, block shaped crystals were obtained after several weeks.
Due to the absence of anomalous scatterers, 2351 Friedel pairs were merged. All H atoms were initially located by difference Fourier synthesis. Subsequently, H atoms bonded to C and O atoms were refined using a riding model, with C—H = 0.95 Å and O—H = 0.84 Å, and with Uiso(H) = 1.2Ueq(C) and 1.5Ueq(O), respectively; H atoms bonded to O atoms were allowed to rotate about the C—O bond. H atoms bonded to N atoms were refined isotropically with Uiso(H) = 1.2Ueq(N).
The synthesis of new compounds by breaking and forming covalent bonds is conventional. A new challenge is creating materials consolidated by weak hydrogen bonds (Aakeröy et al., 2005). The stability of these materials results mainly from the assembly of hydrogen-bonded networks within the structure or arises by cooperative effects as it has been exemplified in the manner of DNA or supramolecular polymers (Prins et al., 2001; Brunsveld et al., 2001). The object of this investigation was the co-crystallization of chelidamic acid Ia and 2,6-diaminopyridine II in order to obtain the
III with an ADA/DAD pattern (A: hydrogen-bond acceptor, D: hydrogen-bond donor). However, the two components formed a salt (Fig. 1), which is reasonable considering the acid-base properties of the starting components. Chelidamic acid can exist in two tautomeric forms Ia and Ib. A search of the Cambridge Structural Database (CSD, Version 5.33 of November 2011, plus two updates; Allen, 2002) yielded no hits for chelidamic acid as neutral 4-hydroxypyridine or 4-pyridone tautomer. The structure of chelidamic acid monohydrate has been found to be zwitterionic [refcode KIXCUP (Hall et al., 2000)] and two crystal structures involve chelidamic acid in coordination complexes (refcodes FEZHEY and FEZHIC). A recent study of three pseudopolymorphs of chelidamic acid has been carried out by Tutughamiarso et al. (2012). In general the different forms of chelidamic acid depend on the pKa values (Norkus et al., 2003). In this study chelidamic acid is doubly deprotonated. The first proton transfer is assumed to be intramolecular (Hall et al., 2000) while the second deprotonation is suggested to occur intermolecular with 2,6-diaminopyridine as proton acceptor. Compound II is known to be reactive in the presence of dicarboxylic acid (Schmid & Mann, 1954) but a reaction with dicarboxylic acids without activation is not expected in this case. In the of the title compound two one-dimensional hydrogen-bond networks are observed, connecting symmetry-equivalent chelidamates (generated by an a glide plane) via O—H···O chains, whilst those fragments are twisted approximately by 60° with respect to each other (Fig. 2). When comparing the symmetry-independent chelidamates with each other, a slight difference in planarity is noticeable. The plane stretching over all non-hydrogen atoms in the N1 or N1' unit shows a mean deviation of 0.053 Å and 0.078 Å [significant outliers: O3 = -0.109 (2), O4 = -0.121 (2) and O1' = -0.105 (2), O3' = 0.178 (2), O4' = 0.155 (2) Å], respectively. The H atom at O5 atom lies in the plane whereas the other H atom at O5' deviates by 0.125 (2) Å from it. In these two cases the aromatic ring atoms including the hydroxy groups were used for the definition of the plane [mean deviation from plane: 0.013 Å for O5 unit and 0.061 Å for O5' unit]. The planarity of the two symmetry-independent 2,6-diaminopyridinium cations is remarkable. A least-squares plane through all atoms of the N11 or N11' fragment yielded a mean deviation of 0.054 and 0.075 Å, respectively. The deviations of the H atoms H11B [0.19 (3) Å] and H22C [–0.17 (2) Å] from the mean plane are probably caused by bifurcated hydrogen bonds with the (also slightly out of plane drifted) O5' atom of chelidamate (Fig. 3). A further investigation of the crystal packing indicates a finite three-dimensional network between the four charged entities in the which run along the a-axis in a zigzag alignment (Fig. 4).For chelidamic acid, see: Tutughamiarso et al. (2012). For chelidamic acid monohydrate, see: Hall et al. (2000). For interaction of chelidamic acid with heavy metal ions, see: Norkus et al. (2003). For supermolecular structures, see: Aakeröy et al. (2005); Brunsveld et al. (2001); Prins et al. (2001); Schmid & Mann (1954). For a description of the Cambridge Structural Database, see: Allen (2002).
Data collection: X-AREA (Stoe & Cie, 2001); cell
X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008) and XP (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip (2010).Fig. 1. A perspective view of the title compound, showing the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Dashed lines indicate hydrogen bonds. | |
Fig. 2. Four planes generated by chelidamates each gliding along the a-axis with at least four fragments. The planes are stretched over the defined N1 and O5 atoms (red or green) or N1' and O5' atoms (yellow or blue) whilst two planes are made up of symmetric chelidamates, which enclose angles of approximately 60°. | |
Fig. 3. DDD–AA hydrogen bond interaction between atoms N1' and N11' of chelidamates and 2,6-diaminopyridininium (left). The out-of-plane drifted hydrogen atoms H11B and H22C; this effect is caused by a strong hydrogen-bond interaction with O4' (right). Red dashed lines indicate hydrogen bonds | |
Fig. 4. Crystal packing of the title compound viewed along the a-axis. Red dashed lines indicate the hydrogen-bond network which interlinks two chelidamates and two 2,6-diaminopyridinium cations to an entity that glides along the a-axis. |
C5H8N3+·C7H4NO5− | F(000) = 1216 |
Mr = 292.26 | Dx = 1.497 Mg m−3 |
Orthorhombic, Pca21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2ac | Cell parameters from 35668 reflections |
a = 14.963 (3) Å | θ = 3.4–25.6° |
b = 8.500 (2) Å | µ = 0.12 mm−1 |
c = 20.385 (4) Å | T = 173 K |
V = 2592.7 (9) Å3 | Block, colourless |
Z = 8 | 0.40 × 0.30 × 0.20 mm |
Stoe IPDS II two-circle diffractometer | 2243 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.071 |
Graphite monochromator | θmax = 25.6°, θmin = 3.4° |
ω scans | h = −18→18 |
33672 measured reflections | k = −10→10 |
2510 independent reflections | l = −24→24 |
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)] = 0.036 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.083 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0555P)2] where P = (Fo2 + 2Fc2)/3 |
2510 reflections | (Δ/σ)max < 0.001 |
417 parameters | Δρmax = 0.16 e Å−3 |
1 restraint | Δρmin = −0.23 e Å−3 |
C5H8N3+·C7H4NO5− | V = 2592.7 (9) Å3 |
Mr = 292.26 | Z = 8 |
Orthorhombic, Pca21 | Mo Kα radiation |
a = 14.963 (3) Å | µ = 0.12 mm−1 |
b = 8.500 (2) Å | T = 173 K |
c = 20.385 (4) Å | 0.40 × 0.30 × 0.20 mm |
Stoe IPDS II two-circle diffractometer | 2243 reflections with I > 2σ(I) |
33672 measured reflections | Rint = 0.071 |
2510 independent reflections |
R[F2 > 2σ(F2)] = 0.036 | 1 restraint |
wR(F2) = 0.083 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.16 e Å−3 |
2510 reflections | Δρmin = −0.23 e Å−3 |
417 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.28490 (16) | 0.3325 (3) | 0.29385 (13) | 0.0189 (5) | |
H1N | 0.327 (2) | 0.296 (4) | 0.3201 (19) | 0.023* | |
O1 | 0.45940 (13) | 0.3882 (3) | 0.28520 (12) | 0.0274 (5) | |
O2 | 0.23936 (14) | 0.1442 (3) | 0.39526 (12) | 0.0290 (5) | |
O3 | 0.44259 (14) | 0.5304 (3) | 0.19256 (12) | 0.0247 (5) | |
O4 | 0.09524 (13) | 0.1412 (3) | 0.36286 (12) | 0.0284 (5) | |
O5 | 0.10342 (13) | 0.5135 (3) | 0.16602 (12) | 0.0218 (5) | |
HO5 | 0.0514 | 0.4868 | 0.1767 | 0.033* | |
C2 | 0.31328 (18) | 0.4270 (3) | 0.24492 (15) | 0.0179 (6) | |
C3 | 0.2527 (2) | 0.4901 (4) | 0.20125 (18) | 0.0188 (7) | |
H3 | 0.2726 | 0.5567 | 0.1668 | 0.023* | |
C4 | 0.16070 (18) | 0.4548 (4) | 0.20811 (16) | 0.0180 (6) | |
C5 | 0.13420 (18) | 0.3556 (4) | 0.26059 (15) | 0.0179 (6) | |
H5 | 0.0728 | 0.3311 | 0.2667 | 0.021* | |
C6 | 0.19726 (18) | 0.2947 (4) | 0.30257 (14) | 0.0180 (6) | |
C7 | 0.41412 (18) | 0.4510 (4) | 0.24134 (15) | 0.0199 (6) | |
C8 | 0.17574 (19) | 0.1826 (4) | 0.35877 (15) | 0.0216 (7) | |
N11 | 0.05045 (16) | −0.0540 (3) | 0.46143 (14) | 0.0211 (6) | |
H11A | 0.077 (3) | 0.005 (4) | 0.426 (2) | 0.025* | |
N21 | −0.0790 (2) | −0.0368 (4) | 0.40028 (18) | 0.0333 (7) | |
H21A | −0.051 (3) | 0.024 (6) | 0.375 (3) | 0.040* | |
H21B | −0.136 (3) | −0.060 (5) | 0.395 (2) | 0.040* | |
N22 | 0.18961 (18) | −0.0644 (4) | 0.51078 (16) | 0.0298 (7) | |
H22A | 0.209 (3) | 0.006 (5) | 0.472 (2) | 0.036* | |
H22B | 0.222 (3) | −0.080 (5) | 0.545 (2) | 0.036* | |
C12 | −0.0384 (2) | −0.0884 (4) | 0.45527 (17) | 0.0229 (7) | |
C13 | −0.0804 (2) | −0.1742 (4) | 0.50451 (18) | 0.0297 (8) | |
H13 | −0.1427 | −0.1958 | 0.5027 | 0.036* | |
C14 | −0.0283 (2) | −0.2278 (4) | 0.55677 (17) | 0.0310 (8) | |
H14 | −0.0561 | −0.2872 | 0.5906 | 0.037* | |
C15 | 0.0634 (2) | −0.1973 (4) | 0.56117 (16) | 0.0283 (7) | |
H15 | 0.0979 | −0.2375 | 0.5965 | 0.034* | |
C16 | 0.1027 (2) | −0.1060 (4) | 0.51205 (16) | 0.0226 (7) | |
N1' | 0.45633 (16) | 0.8257 (3) | 0.62319 (13) | 0.0193 (5) | |
H1'N | 0.420 (2) | 0.782 (4) | 0.5953 (19) | 0.023* | |
O1' | 0.27918 (14) | 0.8557 (3) | 0.63201 (12) | 0.0289 (5) | |
O2' | 0.50769 (14) | 0.6478 (3) | 0.52175 (12) | 0.0322 (6) | |
O3' | 0.29024 (14) | 0.9805 (3) | 0.72949 (13) | 0.0273 (6) | |
O4' | 0.65252 (14) | 0.6636 (3) | 0.55187 (13) | 0.0323 (6) | |
O5' | 0.62710 (14) | 1.0323 (3) | 0.75228 (13) | 0.0272 (6) | |
HO5' | 0.6794 | 1.0350 | 0.7373 | 0.041* | |
C2' | 0.42327 (18) | 0.9094 (4) | 0.67481 (15) | 0.0190 (6) | |
C3' | 0.47987 (19) | 0.9782 (4) | 0.71856 (18) | 0.0195 (7) | |
H3' | 0.4569 | 1.0356 | 0.7548 | 0.023* | |
C4' | 0.57377 (18) | 0.9632 (4) | 0.70940 (15) | 0.0180 (6) | |
C5' | 0.60514 (18) | 0.8727 (4) | 0.65626 (16) | 0.0208 (7) | |
H5' | 0.6675 | 0.8597 | 0.6494 | 0.025* | |
C6' | 0.54480 (19) | 0.8037 (4) | 0.61458 (15) | 0.0188 (6) | |
C7' | 0.32115 (18) | 0.9150 (4) | 0.67830 (16) | 0.0193 (6) | |
C8' | 0.57095 (19) | 0.6954 (4) | 0.55701 (16) | 0.0222 (7) | |
N11' | 0.69417 (17) | 0.4557 (3) | 0.45602 (14) | 0.0216 (6) | |
H11B | 0.670 (3) | 0.530 (5) | 0.482 (2) | 0.026* | |
N21' | 0.55525 (19) | 0.4508 (4) | 0.40698 (16) | 0.0290 (6) | |
H21C | 0.538 (3) | 0.514 (5) | 0.436 (3) | 0.035* | |
H21D | 0.520 (3) | 0.426 (5) | 0.373 (2) | 0.035* | |
N22' | 0.82341 (19) | 0.4676 (4) | 0.51780 (17) | 0.0304 (7) | |
H22C | 0.788 (3) | 0.512 (5) | 0.551 (3) | 0.036* | |
H22D | 0.886 (3) | 0.442 (5) | 0.517 (2) | 0.036* | |
C12' | 0.6415 (2) | 0.4059 (4) | 0.40541 (16) | 0.0221 (6) | |
C13' | 0.6800 (2) | 0.3114 (4) | 0.35694 (16) | 0.0279 (7) | |
H13' | 0.6452 | 0.2723 | 0.3215 | 0.034* | |
C14' | 0.7703 (2) | 0.2761 (4) | 0.36190 (18) | 0.0314 (8) | |
H14' | 0.7971 | 0.2140 | 0.3285 | 0.038* | |
C15' | 0.8230 (2) | 0.3275 (4) | 0.41358 (18) | 0.0298 (8) | |
H15' | 0.8849 | 0.3027 | 0.4154 | 0.036* | |
C16' | 0.7828 (2) | 0.4164 (4) | 0.46261 (16) | 0.0225 (7) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0105 (11) | 0.0253 (14) | 0.0208 (13) | −0.0001 (10) | −0.0017 (10) | 0.0004 (11) |
O1 | 0.0146 (10) | 0.0403 (14) | 0.0275 (12) | −0.0003 (9) | −0.0053 (9) | 0.0016 (10) |
O2 | 0.0183 (10) | 0.0420 (15) | 0.0267 (12) | 0.0010 (9) | −0.0020 (9) | 0.0121 (11) |
O3 | 0.0119 (10) | 0.0352 (13) | 0.0269 (13) | −0.0014 (8) | 0.0029 (8) | 0.0075 (10) |
O4 | 0.0162 (10) | 0.0398 (14) | 0.0292 (12) | −0.0061 (9) | −0.0008 (9) | 0.0118 (11) |
O5 | 0.0100 (10) | 0.0319 (13) | 0.0233 (13) | 0.0007 (8) | −0.0011 (9) | 0.0082 (9) |
C2 | 0.0142 (13) | 0.0207 (15) | 0.0187 (14) | −0.0009 (10) | 0.0006 (11) | −0.0032 (12) |
C3 | 0.0167 (15) | 0.0236 (17) | 0.0162 (17) | −0.0003 (12) | 0.0007 (12) | 0.0026 (12) |
C4 | 0.0130 (14) | 0.0209 (16) | 0.0202 (16) | 0.0043 (11) | 0.0004 (11) | −0.0016 (13) |
C5 | 0.0106 (12) | 0.0206 (15) | 0.0225 (15) | −0.0015 (10) | 0.0003 (11) | −0.0018 (12) |
C6 | 0.0114 (13) | 0.0218 (16) | 0.0208 (15) | 0.0005 (11) | −0.0010 (11) | −0.0010 (12) |
C7 | 0.0106 (12) | 0.0265 (16) | 0.0224 (15) | 0.0010 (11) | −0.0006 (11) | −0.0038 (13) |
C8 | 0.0201 (15) | 0.0253 (17) | 0.0195 (16) | 0.0008 (12) | 0.0025 (12) | −0.0001 (13) |
N11 | 0.0178 (12) | 0.0252 (15) | 0.0203 (15) | −0.0013 (10) | 0.0005 (10) | 0.0053 (12) |
N21 | 0.0213 (14) | 0.0440 (19) | 0.0345 (18) | −0.0053 (14) | −0.0044 (12) | 0.0115 (17) |
N22 | 0.0223 (14) | 0.0395 (19) | 0.0276 (17) | −0.0028 (12) | −0.0058 (12) | 0.0064 (15) |
C12 | 0.0200 (14) | 0.0222 (17) | 0.0264 (16) | −0.0006 (12) | −0.0004 (12) | −0.0014 (14) |
C13 | 0.0250 (15) | 0.0327 (19) | 0.0315 (19) | −0.0076 (13) | 0.0048 (13) | 0.0032 (16) |
C14 | 0.0383 (18) | 0.031 (2) | 0.0241 (18) | −0.0091 (15) | 0.0017 (15) | 0.0039 (15) |
C15 | 0.0333 (17) | 0.0291 (19) | 0.0226 (18) | −0.0006 (14) | −0.0017 (14) | 0.0035 (14) |
C16 | 0.0253 (15) | 0.0232 (16) | 0.0193 (16) | 0.0026 (13) | −0.0032 (12) | 0.0000 (14) |
N1' | 0.0141 (11) | 0.0254 (14) | 0.0183 (13) | −0.0019 (10) | −0.0012 (10) | −0.0032 (11) |
O1' | 0.0160 (9) | 0.0417 (15) | 0.0289 (13) | 0.0004 (9) | −0.0073 (9) | −0.0017 (11) |
O2' | 0.0238 (11) | 0.0443 (15) | 0.0286 (13) | −0.0032 (10) | 0.0007 (10) | −0.0118 (11) |
O3' | 0.0122 (10) | 0.0409 (14) | 0.0288 (14) | 0.0006 (9) | 0.0015 (9) | −0.0072 (11) |
O4' | 0.0194 (10) | 0.0435 (15) | 0.0341 (13) | 0.0019 (10) | 0.0035 (10) | −0.0177 (12) |
O5' | 0.0110 (9) | 0.0443 (14) | 0.0263 (14) | −0.0065 (9) | 0.0008 (9) | −0.0127 (11) |
C2' | 0.0137 (13) | 0.0208 (15) | 0.0225 (15) | 0.0011 (11) | 0.0015 (12) | 0.0036 (13) |
C3' | 0.0112 (13) | 0.0237 (16) | 0.0237 (19) | 0.0010 (11) | 0.0025 (12) | −0.0017 (13) |
C4' | 0.0132 (14) | 0.0249 (16) | 0.0159 (16) | −0.0005 (12) | 0.0008 (11) | −0.0007 (13) |
C5' | 0.0121 (14) | 0.0257 (16) | 0.0247 (16) | 0.0008 (12) | 0.0032 (11) | −0.0001 (13) |
C6' | 0.0142 (13) | 0.0207 (16) | 0.0215 (16) | 0.0002 (11) | 0.0039 (11) | 0.0018 (12) |
C7' | 0.0138 (13) | 0.0216 (15) | 0.0225 (15) | −0.0005 (11) | −0.0011 (12) | 0.0037 (13) |
C8' | 0.0185 (14) | 0.0269 (17) | 0.0213 (16) | −0.0038 (12) | 0.0019 (12) | −0.0049 (13) |
N11' | 0.0196 (13) | 0.0227 (15) | 0.0225 (15) | 0.0015 (11) | 0.0006 (10) | −0.0039 (13) |
N21' | 0.0238 (14) | 0.0394 (18) | 0.0239 (16) | 0.0041 (12) | −0.0062 (12) | −0.0083 (14) |
N22' | 0.0180 (14) | 0.0435 (18) | 0.0297 (18) | 0.0012 (13) | −0.0043 (12) | −0.0067 (16) |
C12' | 0.0264 (15) | 0.0209 (16) | 0.0190 (16) | −0.0027 (12) | 0.0018 (12) | 0.0029 (14) |
C13' | 0.0363 (17) | 0.0253 (18) | 0.0222 (17) | −0.0002 (14) | −0.0042 (13) | −0.0022 (14) |
C14' | 0.0385 (19) | 0.0288 (19) | 0.0269 (18) | 0.0083 (14) | 0.0077 (14) | −0.0056 (15) |
C15' | 0.0248 (15) | 0.0298 (19) | 0.035 (2) | 0.0060 (13) | 0.0028 (14) | −0.0004 (15) |
C16' | 0.0214 (14) | 0.0202 (16) | 0.0258 (17) | −0.0016 (11) | 0.0026 (12) | 0.0019 (14) |
N1—C2 | 1.349 (4) | N1'—C6' | 1.348 (4) |
N1—C6 | 1.362 (4) | N1'—C2' | 1.363 (4) |
N1—H1N | 0.88 (4) | N1'—H1'N | 0.87 (4) |
O1—C7 | 1.242 (4) | O1'—C7' | 1.241 (4) |
O2—C8 | 1.251 (4) | O2'—C8' | 1.256 (4) |
O3—C7 | 1.275 (4) | O3'—C7' | 1.270 (4) |
O4—C8 | 1.258 (4) | O4'—C8' | 1.254 (4) |
O5—C4 | 1.311 (4) | O5'—C4' | 1.322 (4) |
O5—HO5 | 0.8400 | O5'—HO5' | 0.8400 |
C2—C3 | 1.379 (4) | C2'—C3' | 1.362 (5) |
C2—C7 | 1.524 (4) | C2'—C7' | 1.530 (4) |
C3—C4 | 1.416 (4) | C3'—C4' | 1.423 (4) |
C3—H3 | 0.9500 | C3'—H3' | 0.9500 |
C4—C5 | 1.419 (5) | C4'—C5' | 1.409 (4) |
C5—C6 | 1.375 (4) | C5'—C6' | 1.372 (4) |
C5—H5 | 0.9500 | C5'—H5' | 0.9500 |
C6—C8 | 1.524 (4) | C6'—C8' | 1.542 (4) |
N11—C12 | 1.367 (4) | N11'—C12' | 1.365 (4) |
N11—C16 | 1.368 (4) | N11'—C16' | 1.374 (4) |
N11—H11A | 0.97 (4) | N11'—H11B | 0.90 (4) |
N21—C12 | 1.349 (5) | N21'—C12' | 1.346 (4) |
N21—H21A | 0.84 (5) | N21'—H21C | 0.84 (5) |
N21—H21B | 0.88 (5) | N21'—H21D | 0.89 (5) |
N22—C16 | 1.349 (4) | N22'—C16' | 1.351 (5) |
N22—H22A | 1.04 (5) | N22'—H22C | 0.94 (5) |
N22—H22B | 0.86 (5) | N22'—H22D | 0.96 (4) |
C12—C13 | 1.391 (5) | C12'—C13' | 1.398 (5) |
C13—C14 | 1.397 (5) | C13'—C14' | 1.388 (5) |
C13—H13 | 0.9500 | C13'—H13' | 0.9500 |
C14—C15 | 1.399 (5) | C14'—C15' | 1.387 (5) |
C14—H14 | 0.9500 | C14'—H14' | 0.9500 |
C15—C16 | 1.396 (5) | C15'—C16' | 1.390 (5) |
C15—H15 | 0.9500 | C15'—H15' | 0.9500 |
C2—N1—C6 | 122.7 (3) | C6'—N1'—C2' | 121.9 (3) |
C2—N1—H1N | 116 (2) | C6'—N1'—H1'N | 118 (2) |
C6—N1—H1N | 121 (2) | C2'—N1'—H1'N | 120 (2) |
C4—O5—HO5 | 109.5 | C4'—O5'—HO5' | 109.5 |
N1—C2—C3 | 120.1 (3) | C3'—C2'—N1' | 120.3 (3) |
N1—C2—C7 | 115.2 (3) | C3'—C2'—C7' | 125.3 (3) |
C3—C2—C7 | 124.6 (3) | N1'—C2'—C7' | 114.5 (3) |
C2—C3—C4 | 119.5 (3) | C2'—C3'—C4' | 119.3 (3) |
C2—C3—H3 | 120.2 | C2'—C3'—H3' | 120.3 |
C4—C3—H3 | 120.2 | C4'—C3'—H3' | 120.3 |
O5—C4—C3 | 119.4 (3) | O5'—C4'—C5' | 123.4 (3) |
O5—C4—C5 | 122.5 (3) | O5'—C4'—C3' | 118.0 (3) |
C3—C4—C5 | 118.2 (3) | C5'—C4'—C3' | 118.6 (3) |
C6—C5—C4 | 120.1 (2) | C6'—C5'—C4' | 119.4 (3) |
C6—C5—H5 | 120.0 | C6'—C5'—H5' | 120.3 |
C4—C5—H5 | 120.0 | C4'—C5'—H5' | 120.3 |
N1—C6—C5 | 119.4 (3) | N1'—C6'—C5' | 120.4 (3) |
N1—C6—C8 | 116.7 (2) | N1'—C6'—C8' | 115.5 (3) |
C5—C6—C8 | 123.9 (3) | C5'—C6'—C8' | 124.0 (3) |
O1—C7—O3 | 127.3 (3) | O1'—C7'—O3' | 128.2 (3) |
O1—C7—C2 | 116.6 (3) | O1'—C7'—C2' | 117.2 (3) |
O3—C7—C2 | 116.0 (3) | O3'—C7'—C2' | 114.5 (3) |
O2—C8—O4 | 128.1 (3) | O4'—C8'—O2' | 128.0 (3) |
O2—C8—C6 | 116.7 (3) | O4'—C8'—C6' | 116.0 (3) |
O4—C8—C6 | 115.3 (3) | O2'—C8'—C6' | 115.9 (3) |
C12—N11—C16 | 123.8 (3) | C12'—N11'—C16' | 123.7 (3) |
C12—N11—H11A | 116 (2) | C12'—N11'—H11B | 116 (3) |
C16—N11—H11A | 120 (2) | C16'—N11'—H11B | 120 (3) |
C12—N21—H21A | 119 (3) | C12'—N21'—H21C | 120 (3) |
C12—N21—H21B | 117 (3) | C12'—N21'—H21D | 118 (3) |
H21A—N21—H21B | 123 (5) | H21C—N21'—H21D | 121 (4) |
C16—N22—H22A | 116 (2) | C16'—N22'—H22C | 118 (3) |
C16—N22—H22B | 119 (3) | C16'—N22'—H22D | 110 (3) |
H22A—N22—H22B | 123 (4) | H22C—N22'—H22D | 131 (4) |
N21—C12—N11 | 116.4 (3) | N21'—C12'—N11' | 116.6 (3) |
N21—C12—C13 | 124.6 (3) | N21'—C12'—C13' | 125.0 (3) |
N11—C12—C13 | 119.0 (3) | N11'—C12'—C13' | 118.4 (3) |
C12—C13—C14 | 118.0 (3) | C14'—C13'—C12' | 118.2 (3) |
C12—C13—H13 | 121.0 | C14'—C13'—H13' | 120.9 |
C14—C13—H13 | 121.0 | C12'—C13'—H13' | 120.9 |
C13—C14—C15 | 122.4 (3) | C15'—C14'—C13' | 122.8 (3) |
C13—C14—H14 | 118.8 | C15'—C14'—H14' | 118.6 |
C15—C14—H14 | 118.8 | C13'—C14'—H14' | 118.6 |
C16—C15—C14 | 118.0 (3) | C14'—C15'—C16' | 118.1 (3) |
C16—C15—H15 | 121.0 | C14'—C15'—H15' | 121.0 |
C14—C15—H15 | 121.0 | C16'—C15'—H15' | 121.0 |
N22—C16—N11 | 116.9 (3) | N22'—C16'—N11' | 115.9 (3) |
N22—C16—C15 | 124.4 (3) | N22'—C16'—C15' | 125.4 (3) |
N11—C16—C15 | 118.7 (3) | N11'—C16'—C15' | 118.7 (3) |
C6—N1—C2—C3 | 0.2 (4) | C6'—N1'—C2'—C3' | 2.1 (5) |
C6—N1—C2—C7 | −177.7 (3) | C6'—N1'—C2'—C7' | −177.1 (3) |
N1—C2—C3—C4 | −0.1 (5) | N1'—C2'—C3'—C4' | 0.7 (5) |
C7—C2—C3—C4 | 177.7 (3) | C7'—C2'—C3'—C4' | 179.8 (3) |
C2—C3—C4—O5 | −179.2 (3) | C2'—C3'—C4'—O5' | 179.4 (3) |
C2—C3—C4—C5 | 0.4 (5) | C2'—C3'—C4'—C5' | −2.1 (5) |
O5—C4—C5—C6 | 178.7 (3) | O5'—C4'—C5'—C6' | 179.3 (3) |
C3—C4—C5—C6 | −0.9 (5) | C3'—C4'—C5'—C6' | 0.8 (5) |
C2—N1—C6—C5 | −0.7 (4) | C2'—N1'—C6'—C5' | −3.4 (5) |
C2—N1—C6—C8 | 178.2 (3) | C2'—N1'—C6'—C8' | 175.3 (3) |
C4—C5—C6—N1 | 1.0 (4) | C4'—C5'—C6'—N1' | 1.9 (5) |
C4—C5—C6—C8 | −177.8 (3) | C4'—C5'—C6'—C8' | −176.7 (3) |
N1—C2—C7—O1 | −3.3 (4) | C3'—C2'—C7'—O1' | 175.0 (3) |
C3—C2—C7—O1 | 178.8 (3) | N1'—C2'—C7'—O1' | −5.8 (4) |
N1—C2—C7—O3 | 175.0 (3) | C3'—C2'—C7'—O3' | −5.3 (4) |
C3—C2—C7—O3 | −2.8 (4) | N1'—C2'—C7'—O3' | 173.9 (3) |
N1—C6—C8—O2 | 5.3 (4) | N1'—C6'—C8'—O4' | −174.3 (3) |
C5—C6—C8—O2 | −175.9 (3) | C5'—C6'—C8'—O4' | 4.4 (5) |
N1—C6—C8—O4 | −175.3 (3) | N1'—C6'—C8'—O2' | 4.5 (4) |
C5—C6—C8—O4 | 3.5 (5) | C5'—C6'—C8'—O2' | −176.8 (3) |
C16—N11—C12—N21 | −175.8 (3) | C16'—N11'—C12'—N21' | 178.1 (3) |
C16—N11—C12—C13 | 3.5 (5) | C16'—N11'—C12'—C13' | −0.9 (5) |
N21—C12—C13—C14 | 176.2 (4) | N21'—C12'—C13'—C14' | 179.6 (3) |
N11—C12—C13—C14 | −3.0 (5) | N11'—C12'—C13'—C14' | −1.5 (5) |
C12—C13—C14—C15 | 0.4 (5) | C12'—C13'—C14'—C15' | 1.6 (5) |
C13—C14—C15—C16 | 1.8 (5) | C13'—C14'—C15'—C16' | 0.9 (5) |
C12—N11—C16—N22 | 178.9 (3) | C12'—N11'—C16'—N22' | −175.9 (3) |
C12—N11—C16—C15 | −1.2 (5) | C12'—N11'—C16'—C15' | 3.4 (5) |
C14—C15—C16—N22 | 178.4 (3) | C14'—C15'—C16'—N22' | 176.0 (3) |
C14—C15—C16—N11 | −1.4 (5) | C14'—C15'—C16'—N11' | −3.2 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
O5—HO5···O3i | 0.84 | 1.67 | 2.495 (3) | 169 |
O5′—HO5′···O3′ii | 0.84 | 1.67 | 2.487 (3) | 163 |
N21—H21B···O2iii | 0.88 (5) | 2.00 (5) | 2.869 (4) | 170 (4) |
N22—H22B···O1′iv | 0.86 (5) | 2.04 (5) | 2.892 (4) | 169 (4) |
N22′—H22D···O2′v | 0.96 (4) | 1.98 (4) | 2.928 (4) | 170 (4) |
N1—H1N···O1 | 0.88 (3) | 2.25 (3) | 2.660 (3) | 108 (3) |
N1—H1N···O2 | 0.88 (3) | 2.39 (4) | 2.702 (4) | 101 (2) |
N1′—H1′N···O1′ | 0.87 (3) | 2.32 (3) | 2.669 (3) | 104 (3) |
N1′—H1′N···O2′ | 0.87 (3) | 2.30 (4) | 2.675 (4) | 106 (2) |
N11—H11A···O4 | 1.01 (4) | 1.71 (3) | 2.691 (4) | 163 (4) |
N11′—H11B···O4′ | 0.86 (3) | 1.88 (3) | 2.707 (4) | 161 (4) |
N21—H21A···O4 | 0.84 (5) | 2.42 (5) | 3.109 (4) | 140 (5) |
N21′—H21C···O2′ | 0.84 (5) | 2.13 (6) | 2.964 (4) | 170 (5) |
N21′—H21D···O1 | 0.90 (4) | 2.03 (4) | 2.916 (4) | 169 (4) |
N22—H22A···O2 | 1.03 (4) | 2.01 (4) | 3.040 (4) | 177 (4) |
N22′—H22C···O4′ | 0.94 (5) | 2.40 (4) | 3.130 (4) | 134 (4) |
Symmetry codes: (i) x−1/2, −y+1, z; (ii) x+1/2, −y+2, z; (iii) x−1/2, −y, z; (iv) x, y−1, z; (v) x+1/2, −y+1, z. |
Experimental details
Crystal data | |
Chemical formula | C5H8N3+·C7H4NO5− |
Mr | 292.26 |
Crystal system, space group | Orthorhombic, Pca21 |
Temperature (K) | 173 |
a, b, c (Å) | 14.963 (3), 8.500 (2), 20.385 (4) |
V (Å3) | 2592.7 (9) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.40 × 0.30 × 0.20 |
Data collection | |
Diffractometer | Stoe IPDS II two-circle |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 33672, 2510, 2243 |
Rint | 0.071 |
(sin θ/λ)max (Å−1) | 0.608 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.083, 1.04 |
No. of reflections | 2510 |
No. of parameters | 417 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.16, −0.23 |
Computer programs: X-AREA (Stoe & Cie, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2008) and XP (Sheldrick, 2008), publCIF (Westrip (2010).
D—H···A | D—H | H···A | D···A | D—H···A |
O5—HO5···O3i | 0.84 | 1.67 | 2.495 (3) | 168.5 |
O5'—HO5'···O3'ii | 0.84 | 1.67 | 2.487 (3) | 163.0 |
N21—H21B···O2iii | 0.88 (5) | 2.00 (5) | 2.869 (4) | 170 (4) |
N22—H22B···O1'iv | 0.86 (5) | 2.04 (5) | 2.892 (4) | 169 (4) |
N22'—H22D···O2'v | 0.96 (4) | 1.98 (4) | 2.928 (4) | 170 (4) |
N1—H1N···O1 | 0.88 (3) | 2.25 (3) | 2.660 (3) | 108 (3) |
N1—H1N···O2 | 0.88 (3) | 2.39 (4) | 2.702 (4) | 101 (2) |
N1'—H1'N···O1' | 0.87 (3) | 2.32 (3) | 2.669 (3) | 104 (3) |
N1'—H1'N···O2' | 0.87 (3) | 2.30 (4) | 2.675 (4) | 106 (2) |
N11—H11A···O4 | 1.01 (4) | 1.71 (3) | 2.691 (4) | 163 (4) |
N11'—H11B···O4' | 0.86 (3) | 1.88 (3) | 2.707 (4) | 161 (4) |
N21—H21A···O4 | 0.84 (5) | 2.42 (5) | 3.109 (4) | 140 (5) |
N21'—H21C···O2' | 0.84 (5) | 2.13 (6) | 2.964 (4) | 170 (5) |
N21'—H21D···O1 | 0.90 (4) | 2.03 (4) | 2.916 (4) | 169 (4) |
N22—H22A···O2 | 1.03 (4) | 2.01 (4) | 3.040 (4) | 177 (4) |
N22'—H22C···O4' | 0.94 (5) | 2.40 (4) | 3.130 (4) | 134 (4) |
Symmetry codes: (i) x−1/2, −y+1, z; (ii) x+1/2, −y+2, z; (iii) x−1/2, −y, z; (iv) x, y−1, z; (v) x+1/2, −y+1, z. |
Acknowledgements
We thank Professor Dr Ernst Egert for fruitful advice and support.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The synthesis of new compounds by breaking and forming covalent bonds is conventional. A new challenge is creating materials consolidated by weak hydrogen bonds (Aakeröy et al., 2005). The stability of these materials results mainly from the assembly of hydrogen-bonded networks within the structure or arises by cooperative effects as it has been exemplified in the manner of DNA or supramolecular polymers (Prins et al., 2001; Brunsveld et al., 2001). The object of this investigation was the co-crystallization of chelidamic acid Ia and 2,6-diaminopyridine II in order to obtain the co-crystal III with an ADA/DAD pattern (A: hydrogen-bond acceptor, D: hydrogen-bond donor). However, the two components formed a salt (Fig. 1), which is reasonable considering the acid-base properties of the starting components. Chelidamic acid can exist in two tautomeric forms Ia and Ib. A search of the Cambridge Structural Database (CSD, Version 5.33 of November 2011, plus two updates; Allen, 2002) yielded no hits for chelidamic acid as neutral 4-hydroxypyridine or 4-pyridone tautomer. The structure of chelidamic acid monohydrate has been found to be zwitterionic [refcode KIXCUP (Hall et al., 2000)] and two crystal structures involve chelidamic acid in coordination complexes (refcodes FEZHEY and FEZHIC). A recent study of three pseudopolymorphs of chelidamic acid has been carried out by Tutughamiarso et al. (2012). In general the different forms of chelidamic acid depend on the pKa values (Norkus et al., 2003). In this study chelidamic acid is doubly deprotonated. The first proton transfer is assumed to be intramolecular (Hall et al., 2000) while the second deprotonation is suggested to occur intermolecular with 2,6-diaminopyridine as proton acceptor. Compound II is known to be reactive in the presence of dicarboxylic acid anhydrides (Schmid & Mann, 1954) but a reaction with dicarboxylic acids without activation is not expected in this case. In the crystal structure of the title compound two one-dimensional hydrogen-bond networks are observed, connecting symmetry-equivalent chelidamates (generated by an a glide plane) via O—H···O chains, whilst those fragments are twisted approximately by 60° with respect to each other (Fig. 2). When comparing the symmetry-independent chelidamates with each other, a slight difference in planarity is noticeable. The plane stretching over all non-hydrogen atoms in the N1 or N1' unit shows a mean deviation of 0.053 Å and 0.078 Å [significant outliers: O3 = -0.109 (2), O4 = -0.121 (2) and O1' = -0.105 (2), O3' = 0.178 (2), O4' = 0.155 (2) Å], respectively. The H atom at O5 atom lies in the plane whereas the other H atom at O5' deviates by 0.125 (2) Å from it. In these two cases the aromatic ring atoms including the hydroxy groups were used for the definition of the plane [mean deviation from plane: 0.013 Å for O5 unit and 0.061 Å for O5' unit]. The planarity of the two symmetry-independent 2,6-diaminopyridinium cations is remarkable. A least-squares plane through all atoms of the N11 or N11' fragment yielded a mean deviation of 0.054 and 0.075 Å, respectively. The deviations of the H atoms H11B [0.19 (3) Å] and H22C [–0.17 (2) Å] from the mean plane are probably caused by bifurcated hydrogen bonds with the (also slightly out of plane drifted) O5' atom of chelidamate (Fig. 3). A further investigation of the crystal packing indicates a finite three-dimensional network between the four charged entities in the asymmetric unit, which run along the a-axis in a zigzag alignment (Fig. 4).