organic compounds
4-Methylpyridinium 2-carboxy-4,5-dichlorobenzoate monohydrate
aFaculty of Science and Technology, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia
*Correspondence e-mail: g.smith@qut.edu.au
In the structure of the 1:1 proton-transfer compound of 4-methylpyridine (γ-picoline) with 4,5-dichlorophthalic acid, C6H8N+·C8H3Cl2O4−·H2O, determined at 200 K, the 4,5-dichlorophthalate anions are bridged by the water molecule through O—H⋯Ocarboxyl hydrogen bonds, giving zigzag chains which extend along the c-axis direction. The 4-methylpyridinium cations are linked to the chains through single N—H⋯Owater hydrogen bonds and occupy the voids within the chains in the one-dimensional structure. The anions have the common `planar' conformation with a short intramolecular O—H⋯Ocarboxyl hydrogen bond.
Related literature
For the structures of other hydrogen 4,5-dichlorophthalate salts, see: Mallinson et al. (2003); Bozkurt et al. (2006); Smith et al. (2007, 2008a,b, 2009, 2009a,b); Smith & Wermuth (2010a,b).
Experimental
Crystal data
|
Refinement
|
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON.
Supporting information
https://doi.org/10.1107/S1600536810015503/jj2029sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810015503/jj2029Isup2.hkl
The title compound (I) was synthesized by heating together for 10 min under reflux 1 mmol quantities of γ-picoline and 4,5-dichlorophthalic acid in 50 ml of methanol. The product after complete room-temperature evaporation of the hot-filtered solution was microcrystalline. Recrystallization from water gave colourless flat needles (m.p. 445 K) from which a specimen suitable for X-ray analysis was cleaved.
Hydrogen atoms potentially involved in hydrogen-bonding interactions were located by difference methods and their positional and isotropic displacement parameters were refined. Other H atoms were included in the
at calculated positions [C–Haromatic = 0.93 Å and C–Haliphatic = 0.98 Å] and treated as riding models with Uiso(H) = 1.2Ueq(C).The 1:1 proton-transfer compounds of 4,5-dichlorophthalic acid (DCPA) with the nitrogen Lewis bases commonly have low-dimensional hydrogen-bonded structures (Mallinson et al., 2003; Bozkurt et al., 2006; Smith et al., 2007, 2008a, 2008b, 2009a, 2009b; Smith et al., 2009; Smith & Wermuth, 2010a, 2010b). With the majority of these structures, e.g. the brucinium salt (Smith et al., 2007), the DCPA anions are essentially planar (the 'planar' conformation) with short intramolecular carboxylic acid O–H···Ocarboxyl hydrogen bonds. These features were also found in the structure of the hydrated 1:1 proton-transfer compound of DCPA with 4-methylpyridine (γ-picoline), the title compound C6H8N+ C8H3Cl2O4- . H2O (I), reported here.
In (I) (Fig. 1), the 4,5-dichlorophthalate anions are bridged by the water molecule through O–H···Ocarboxyl hydrogen bonds giving zig-zag chains which extend along the c axial direction of the π–π ring stacking interactions such as are present in some of the DCPA compounds.
(Fig. 2). The 4-methylpyridine cations are linked to the chains through single N–H···Owater hydrogen bonds and occupy the voids formed within the chains, in the one-dimensional structure. There are no cation–anionThe DCPA anion has the 'planar' conformation [torsion angles C2–C1–C11–O11, -173.2 (3)°: C1–C2–C21–O22, 169.9 (3)°], with the short intramolecular O–H···Ocarboxyl hydrogen bond [2.376 (4) Å]. Associated with this bond is a significant distortion of the exo-C1 and C2 bond angles [C1–C2–C21, 128.9 (3)° and C2–C1–C11, 128.8 (3)°]. This and a lengthening of the C1–C11 and C2–C21 bonds [1.527 (5) and 1.531 (5) Å] are features inherent in the 'planar' DCPA anions in the overall series of 1:1 proton-transfer compounds.
For the structures of other hydrogen 4,5-dichlorophthalate salts, see: Mallinson et al. (2003); Bozkurt et al. (2006); Smith et al. (2007, 2008a,b, 2009, 2009a,b); Smith & Wermuth (2010a,b).
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell
CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).C6H8N+·C8H3Cl2O4−·H2O | F(000) = 712 |
Mr = 346.15 | Dx = 1.560 Mg m−3 |
Monoclinic, P21/n | Melting point: 445 K |
Hall symbol: -P 2yn | Mo Kα radiation, λ = 0.71073 Å |
a = 3.8398 (3) Å | Cell parameters from 4516 reflections |
b = 29.5531 (17) Å | θ = 3.1–28.7° |
c = 12.9855 (7) Å | µ = 0.46 mm−1 |
β = 90.054 (6)° | T = 200 K |
V = 1473.57 (16) Å3 | Plate, colourless |
Z = 4 | 0.30 × 0.20 × 0.08 mm |
Oxford Diffraction Gemini-S CCD-detector diffractometer | 2579 independent reflections |
Radiation source: Enhance (Mo) X-ray source | 2156 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
Detector resolution: 16.08 pixels mm-1 | θmax = 25.0°, θmin = 3.1° |
ω scans | h = −4→4 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | k = −35→31 |
Tmin = 0.930, Tmax = 0.980 | l = −15→15 |
8898 measured reflections |
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)] = 0.045 | Hydrogen site location: geom' |
wR(F2) = 0.129 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.29 | w = 1/[σ2(Fo2) + (0.042P)2 + 1.7305P] where P = (Fo2 + 2Fc2)/3 |
2579 reflections | (Δ/σ)max < 0.001 |
215 parameters | Δρmax = 0.24 e Å−3 |
0 restraints | Δρmin = −0.33 e Å−3 |
C6H8N+·C8H3Cl2O4−·H2O | V = 1473.57 (16) Å3 |
Mr = 346.15 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 3.8398 (3) Å | µ = 0.46 mm−1 |
b = 29.5531 (17) Å | T = 200 K |
c = 12.9855 (7) Å | 0.30 × 0.20 × 0.08 mm |
β = 90.054 (6)° |
Oxford Diffraction Gemini-S CCD-detector diffractometer | 2579 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2156 reflections with I > 2σ(I) |
Tmin = 0.930, Tmax = 0.980 | Rint = 0.021 |
8898 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.129 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.29 | Δρmax = 0.24 e Å−3 |
2579 reflections | Δρmin = −0.33 e Å−3 |
215 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 esds 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 | ||
Cl4 | 0.1942 (3) | −0.02601 (3) | 0.63754 (7) | 0.0379 (3) | |
Cl5 | −0.1079 (2) | 0.00515 (3) | 0.85706 (7) | 0.0372 (3) | |
O11 | 0.0394 (8) | 0.17470 (9) | 0.8599 (2) | 0.0471 (10) | |
O12 | 0.2068 (8) | 0.20432 (9) | 0.7127 (2) | 0.0490 (10) | |
O21 | 0.4257 (8) | 0.18118 (9) | 0.5499 (2) | 0.0504 (10) | |
O22 | 0.6118 (7) | 0.11959 (9) | 0.47323 (19) | 0.0399 (9) | |
C1 | 0.1694 (8) | 0.12249 (11) | 0.7262 (2) | 0.0233 (10) | |
C2 | 0.3066 (8) | 0.10876 (11) | 0.6304 (2) | 0.0225 (10) | |
C3 | 0.3086 (8) | 0.06268 (11) | 0.6068 (2) | 0.0249 (10) | |
C4 | 0.1817 (8) | 0.03024 (11) | 0.6731 (3) | 0.0252 (10) | |
C5 | 0.0513 (8) | 0.04386 (11) | 0.7687 (2) | 0.0252 (10) | |
C6 | 0.0428 (8) | 0.08917 (11) | 0.7929 (2) | 0.0254 (10) | |
C11 | 0.1371 (9) | 0.17020 (12) | 0.7704 (3) | 0.0328 (11) | |
C21 | 0.4622 (9) | 0.13795 (12) | 0.5446 (3) | 0.0291 (11) | |
N1A | 1.1032 (8) | 0.19332 (11) | 0.2708 (3) | 0.0411 (11) | |
C2A | 1.2276 (11) | 0.21031 (13) | 0.1826 (3) | 0.0447 (14) | |
C3A | 1.3735 (9) | 0.18251 (13) | 0.1103 (3) | 0.0370 (12) | |
C4A | 1.3940 (8) | 0.13645 (12) | 0.1288 (2) | 0.0282 (10) | |
C5A | 1.2671 (9) | 0.12034 (12) | 0.2211 (3) | 0.0333 (11) | |
C6A | 1.1180 (9) | 0.14896 (14) | 0.2913 (3) | 0.0369 (11) | |
C41A | 1.5391 (10) | 0.10520 (15) | 0.0494 (3) | 0.0463 (14) | |
O1W | 0.7863 (9) | 0.23983 (11) | 0.4193 (2) | 0.0462 (10) | |
H3 | 0.39930 | 0.05350 | 0.54380 | 0.0300* | |
H6 | −0.05070 | 0.09800 | 0.85580 | 0.0300* | |
H21 | 0.334 (15) | 0.191 (2) | 0.618 (5) | 0.100 (19)* | |
H1A | 1.012 (12) | 0.211 (2) | 0.315 (4) | 0.049 (10)* | |
H2A | 1.21470 | 0.24130 | 0.17040 | 0.0540* | |
H3A | 1.45850 | 0.19450 | 0.04900 | 0.0450* | |
H5A | 1.28280 | 0.08960 | 0.23580 | 0.0400* | |
H6A | 1.02810 | 0.13770 | 0.35270 | 0.0440* | |
H41A | 1.61710 | 0.12240 | −0.00890 | 0.0560* | |
H42A | 1.36170 | 0.08430 | 0.02790 | 0.0560* | |
H43A | 1.73170 | 0.08870 | 0.07810 | 0.0560* | |
H11W | 0.666 (13) | 0.2227 (18) | 0.449 (4) | 0.065 (17)* | |
H12W | 0.694 (11) | 0.2626 (17) | 0.405 (3) | 0.046 (14)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl4 | 0.0516 (6) | 0.0224 (4) | 0.0396 (5) | −0.0018 (4) | 0.0113 (4) | −0.0043 (4) |
Cl5 | 0.0483 (5) | 0.0316 (5) | 0.0318 (5) | −0.0034 (4) | 0.0108 (4) | 0.0091 (4) |
O11 | 0.074 (2) | 0.0310 (15) | 0.0363 (16) | −0.0029 (13) | 0.0195 (14) | −0.0095 (12) |
O12 | 0.084 (2) | 0.0225 (14) | 0.0406 (16) | 0.0024 (13) | 0.0133 (15) | 0.0012 (12) |
O21 | 0.083 (2) | 0.0280 (15) | 0.0403 (17) | −0.0001 (14) | 0.0222 (15) | 0.0098 (12) |
O22 | 0.0534 (16) | 0.0394 (15) | 0.0269 (14) | 0.0010 (12) | 0.0122 (12) | 0.0059 (11) |
C1 | 0.0232 (17) | 0.0233 (17) | 0.0234 (17) | 0.0009 (13) | −0.0027 (13) | 0.0001 (13) |
C2 | 0.0225 (16) | 0.0244 (17) | 0.0206 (17) | 0.0021 (13) | −0.0019 (13) | 0.0042 (13) |
C3 | 0.0273 (17) | 0.0264 (18) | 0.0209 (16) | 0.0014 (13) | 0.0039 (13) | −0.0017 (13) |
C4 | 0.0281 (17) | 0.0212 (17) | 0.0264 (17) | 0.0023 (13) | 0.0023 (13) | −0.0015 (13) |
C5 | 0.0268 (17) | 0.0249 (17) | 0.0240 (17) | 0.0002 (13) | 0.0028 (13) | 0.0057 (14) |
C6 | 0.0256 (17) | 0.0327 (19) | 0.0179 (16) | 0.0014 (14) | 0.0017 (13) | −0.0036 (14) |
C11 | 0.039 (2) | 0.0253 (19) | 0.034 (2) | 0.0018 (15) | 0.0015 (16) | −0.0026 (15) |
C21 | 0.0315 (19) | 0.032 (2) | 0.0237 (18) | −0.0023 (14) | 0.0016 (14) | 0.0051 (15) |
N1A | 0.0374 (18) | 0.043 (2) | 0.043 (2) | 0.0010 (14) | −0.0022 (15) | −0.0190 (16) |
C2A | 0.046 (2) | 0.029 (2) | 0.059 (3) | −0.0040 (17) | 0.001 (2) | 0.0014 (19) |
C3A | 0.037 (2) | 0.040 (2) | 0.034 (2) | −0.0036 (16) | 0.0039 (16) | 0.0114 (17) |
C4A | 0.0237 (17) | 0.038 (2) | 0.0228 (17) | −0.0011 (14) | −0.0019 (13) | −0.0018 (15) |
C5A | 0.0339 (19) | 0.032 (2) | 0.034 (2) | −0.0021 (15) | −0.0002 (16) | 0.0050 (16) |
C6A | 0.036 (2) | 0.050 (2) | 0.0248 (19) | −0.0044 (17) | 0.0016 (15) | 0.0032 (17) |
C41A | 0.037 (2) | 0.059 (3) | 0.043 (2) | 0.0042 (19) | 0.0065 (18) | −0.013 (2) |
O1W | 0.078 (2) | 0.0254 (16) | 0.0352 (16) | 0.0033 (16) | 0.0159 (15) | 0.0043 (13) |
Cl4—C4 | 1.726 (3) | C3—C4 | 1.378 (5) |
Cl5—C5 | 1.732 (3) | C4—C5 | 1.398 (5) |
O11—C11 | 1.229 (5) | C5—C6 | 1.376 (5) |
O12—C11 | 1.285 (5) | C3—H3 | 0.9300 |
O21—C21 | 1.287 (4) | C6—H6 | 0.9300 |
O22—C21 | 1.218 (5) | C2A—C3A | 1.368 (5) |
O21—H21 | 1.00 (6) | C3A—C4A | 1.385 (5) |
O1W—H12W | 0.78 (5) | C4A—C5A | 1.379 (5) |
O1W—H11W | 0.79 (5) | C4A—C41A | 1.493 (5) |
N1A—C6A | 1.339 (5) | C5A—C6A | 1.369 (5) |
N1A—C2A | 1.339 (5) | C2A—H2A | 0.9300 |
N1A—H1A | 0.85 (5) | C3A—H3A | 0.9300 |
C1—C11 | 1.527 (5) | C5A—H5A | 0.9300 |
C1—C6 | 1.399 (4) | C6A—H6A | 0.9300 |
C1—C2 | 1.411 (4) | C41A—H43A | 0.9600 |
C2—C3 | 1.396 (5) | C41A—H41A | 0.9600 |
C2—C21 | 1.531 (5) | C41A—H42A | 0.9600 |
C21—O21—H21 | 112 (3) | C4—C3—H3 | 119.00 |
H11W—O1W—H12W | 114 (5) | C2—C3—H3 | 119.00 |
C2A—N1A—C6A | 121.5 (4) | C1—C6—H6 | 119.00 |
C2A—N1A—H1A | 120 (4) | C5—C6—H6 | 119.00 |
C6A—N1A—H1A | 119 (4) | N1A—C2A—C3A | 120.6 (4) |
C2—C1—C11 | 128.9 (3) | C2A—C3A—C4A | 119.7 (3) |
C6—C1—C11 | 112.9 (3) | C3A—C4A—C41A | 120.7 (3) |
C2—C1—C6 | 118.3 (3) | C3A—C4A—C5A | 118.1 (3) |
C1—C2—C21 | 128.8 (3) | C5A—C4A—C41A | 121.3 (3) |
C3—C2—C21 | 112.8 (3) | C4A—C5A—C6A | 120.9 (3) |
C1—C2—C3 | 118.4 (3) | N1A—C6A—C5A | 119.4 (4) |
C2—C3—C4 | 122.7 (3) | C3A—C2A—H2A | 120.00 |
C3—C4—C5 | 118.8 (3) | N1A—C2A—H2A | 120.00 |
Cl4—C4—C3 | 119.5 (3) | C2A—C3A—H3A | 120.00 |
Cl4—C4—C5 | 121.7 (3) | C4A—C3A—H3A | 120.00 |
Cl5—C5—C4 | 121.7 (3) | C6A—C5A—H5A | 120.00 |
C4—C5—C6 | 119.4 (3) | C4A—C5A—H5A | 120.00 |
Cl5—C5—C6 | 118.9 (2) | N1A—C6A—H6A | 120.00 |
C1—C6—C5 | 122.4 (3) | C5A—C6A—H6A | 120.00 |
O12—C11—C1 | 119.2 (3) | C4A—C41A—H42A | 109.00 |
O11—C11—C1 | 118.7 (3) | C4A—C41A—H43A | 109.00 |
O11—C11—O12 | 122.1 (3) | C4A—C41A—H41A | 110.00 |
O21—C21—O22 | 122.3 (3) | H41A—C41A—H43A | 110.00 |
O21—C21—C2 | 118.5 (3) | H42A—C41A—H43A | 109.00 |
O22—C21—C2 | 119.2 (3) | H41A—C41A—H42A | 109.00 |
C2A—N1A—C6A—C5A | 0.7 (5) | C1—C2—C21—O22 | 169.9 (3) |
C6A—N1A—C2A—C3A | 0.2 (6) | C1—C2—C3—C4 | 0.1 (5) |
C6—C1—C2—C21 | −179.6 (3) | C2—C3—C4—C5 | −1.2 (5) |
C11—C1—C2—C21 | 0.3 (5) | C2—C3—C4—Cl4 | 180.0 (3) |
C2—C1—C6—C5 | 0.7 (5) | C3—C4—C5—Cl5 | −179.2 (2) |
C11—C1—C6—C5 | −179.1 (3) | Cl4—C4—C5—Cl5 | −0.4 (4) |
C2—C1—C11—O11 | −173.2 (3) | Cl4—C4—C5—C6 | −179.2 (2) |
C2—C1—C11—O12 | 8.0 (5) | C3—C4—C5—C6 | 2.0 (5) |
C6—C1—C11—O11 | 6.7 (4) | C4—C5—C6—C1 | −1.8 (5) |
C11—C1—C2—C3 | 180.0 (3) | Cl5—C5—C6—C1 | 179.4 (2) |
C6—C1—C11—O12 | −172.2 (3) | N1A—C2A—C3A—C4A | −0.3 (6) |
C6—C1—C2—C3 | 0.1 (4) | C2A—C3A—C4A—C5A | −0.5 (5) |
C21—C2—C3—C4 | 179.9 (3) | C2A—C3A—C4A—C41A | 177.6 (3) |
C1—C2—C21—O21 | −11.1 (5) | C41A—C4A—C5A—C6A | −176.6 (3) |
C3—C2—C21—O21 | 169.2 (3) | C3A—C4A—C5A—C6A | 1.5 (5) |
C3—C2—C21—O22 | −9.8 (4) | C4A—C5A—C6A—N1A | −1.6 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A···O1W | 0.85 (5) | 1.82 (5) | 2.663 (5) | 170 (5) |
O1W—H11W···O21 | 0.79 (5) | 2.02 (5) | 2.793 (4) | 168 (5) |
O1W—H12W···O11i | 0.78 (5) | 2.03 (5) | 2.806 (4) | 170 (4) |
O21—H21···O12 | 1.00 (6) | 1.38 (6) | 2.376 (4) | 180 (8) |
C2A—H2A···O12i | 0.93 | 2.59 | 3.243 (5) | 128 |
C2A—H2A···O12ii | 0.93 | 2.54 | 3.147 (5) | 123 |
C6A—H6A···O22 | 0.93 | 2.30 | 3.181 (5) | 158 |
Symmetry codes: (i) x+1/2, −y+1/2, z−1/2; (ii) x+3/2, −y+1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C6H8N+·C8H3Cl2O4−·H2O |
Mr | 346.15 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 200 |
a, b, c (Å) | 3.8398 (3), 29.5531 (17), 12.9855 (7) |
β (°) | 90.054 (6) |
V (Å3) | 1473.57 (16) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.46 |
Crystal size (mm) | 0.30 × 0.20 × 0.08 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini-S CCD-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.930, 0.980 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8898, 2579, 2156 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.129, 1.29 |
No. of reflections | 2579 |
No. of parameters | 215 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.24, −0.33 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A···O1W | 0.85 (5) | 1.82 (5) | 2.663 (5) | 170 (5) |
O1W—H11W···O21 | 0.79 (5) | 2.02 (5) | 2.793 (4) | 168 (5) |
O1W—H12W···O11i | 0.78 (5) | 2.03 (5) | 2.806 (4) | 170 (4) |
O21—H21···O12 | 1.00 (6) | 1.38 (6) | 2.376 (4) | 180 (8) |
Symmetry code: (i) x+1/2, −y+1/2, z−1/2. |
Acknowledgements
The authors acknowledge financial support from the Australian Research Council and the Faculty of Science and Technology, Queensland University of Technology.
References
Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. CrossRef Web of Science IUCr Journals Google Scholar
Bozkurt, E., Kartal, I., Odabaşoğlu, M. & Büyükgüngör, O. (2006). Acta Cryst. E62, o4258–o4260. Web of Science CSD CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Mallinson, P. R., Smith, G. T., Wilson, C. C., Grech, E. & Wozniak, K. (2003). J. Am. Chem. Soc. 125, 4259–4270. Web of Science CSD CrossRef PubMed CAS Google Scholar
Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England. Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Smith, G. & Wermuth, U. D. (2010a). Acta Cryst. E66, o133. Web of Science CSD CrossRef IUCr Journals Google Scholar
Smith, G. & Wermuth, U. D. (2010b). Acta Cryst. E66, o235. Web of Science CSD CrossRef IUCr Journals Google Scholar
Smith, G., Wermuth, U. D. & Sagatys, D. S. (2009). Acta Cryst. C65, o131–o133. Web of Science CSD CrossRef IUCr Journals Google Scholar
Smith, G., Wermuth, U. D. & White, J. M. (2007). Acta Cryst. E63, o4276–o4277. Web of Science CSD CrossRef IUCr Journals Google Scholar
Smith, G., Wermuth, U. D. & White, J. M. (2008a). Acta Cryst. C64, o180–o183. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Smith, G., Wermuth, U. D. & White, J. M. (2008b). Acta Cryst. C64, o532–o536. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Smith, G., Wermuth, U. D. & White, J. M. (2009a). Acta Cryst. C65, o103–o107. Web of Science CSD CrossRef IUCr Journals Google Scholar
Smith, G., Wermuth, U. D. & White, J. M. (2009b). Acta Cryst. E65, o2111. Web of Science CSD CrossRef IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
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 1:1 proton-transfer compounds of 4,5-dichlorophthalic acid (DCPA) with the nitrogen Lewis bases commonly have low-dimensional hydrogen-bonded structures (Mallinson et al., 2003; Bozkurt et al., 2006; Smith et al., 2007, 2008a, 2008b, 2009a, 2009b; Smith et al., 2009; Smith & Wermuth, 2010a, 2010b). With the majority of these structures, e.g. the brucinium salt (Smith et al., 2007), the DCPA anions are essentially planar (the 'planar' conformation) with short intramolecular carboxylic acid O–H···Ocarboxyl hydrogen bonds. These features were also found in the structure of the hydrated 1:1 proton-transfer compound of DCPA with 4-methylpyridine (γ-picoline), the title compound C6H8N+ C8H3Cl2O4- . H2O (I), reported here.
In (I) (Fig. 1), the 4,5-dichlorophthalate anions are bridged by the water molecule through O–H···Ocarboxyl hydrogen bonds giving zig-zag chains which extend along the c axial direction of the unit cell (Fig. 2). The 4-methylpyridine cations are linked to the chains through single N–H···Owater hydrogen bonds and occupy the voids formed within the chains, in the one-dimensional structure. There are no cation–anion π–π ring stacking interactions such as are present in some of the DCPA compounds.
The DCPA anion has the 'planar' conformation [torsion angles C2–C1–C11–O11, -173.2 (3)°: C1–C2–C21–O22, 169.9 (3)°], with the short intramolecular O–H···Ocarboxyl hydrogen bond [2.376 (4) Å]. Associated with this bond is a significant distortion of the exo-C1 and C2 bond angles [C1–C2–C21, 128.9 (3)° and C2–C1–C11, 128.8 (3)°]. This and a lengthening of the C1–C11 and C2–C21 bonds [1.527 (5) and 1.531 (5) Å] are features inherent in the 'planar' DCPA anions in the overall series of 1:1 proton-transfer compounds.