4-Methyl­pyridinium 2-carb­oxy-4,5-dichloro­benzoate monohydrate

Graham Smith; Urs D Wermuth

doi:10.1107/S1600536810015503

. 2010 May 8;66(Pt 6):o1254. doi: 10.1107/S1600536810015503

4-Methylpyridinium 2-carboxy-4,5-dichlorobenzoate monohydrate

Graham Smith ^a,^*, Urs D Wermuth ^a

PMCID: PMC2979372 PMID: 21579358

Abstract

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⋯O_carboxyl 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⋯O_water 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⋯O_carboxyl 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

C₆H₈N⁺·C₈H₃Cl₂O₄ ⁻·H₂O
M _r = 346.15
Monoclinic,
a = 3.8398 (3) Å
b = 29.5531 (17) Å
c = 12.9855 (7) Å
β = 90.054 (6)°
V = 1473.57 (16) Å³
Z = 4
Mo Kα radiation
μ = 0.46 mm⁻¹
T = 200 K
0.30 × 0.20 × 0.08 mm

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.930, T _max = 0.980
8898 measured reflections
2579 independent reflections
2156 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.129
S = 1.29
2579 reflections
215 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▶); cell refinement: 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.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810015503/jj2029sup1.cif

e-66-o1254-sup1.cif^{(18.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810015503/jj2029Isup2.hkl

e-66-o1254-Isup2.hkl^{(124.1KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

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)

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors acknowledge financial support from the Australian Research Council and the Faculty of Science and Technology, Queensland University of Technology.

supplementary crystallographic information

Comment

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···O_carboxyl 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···O_carboxyl 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···O_water 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···O_carboxyl 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.

Experimental

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.