Crystal structure of 4-(di­methyl­amino)­pyridinium 4-amino­benzoate dihydrate

A Thirunavukkarasu; A Silambarasan; R Mohan Kumar; P R Umarani; G Chakkaravarthi

doi:10.1107/S2056989014026310

. 2015 Jan 1;71(Pt 1):o26–o27. doi: 10.1107/S2056989014026310

Crystal structure of 4-(dimethylamino)pyridinium 4-aminobenzoate dihydrate

A Thirunavukkarasu ^a, A Silambarasan ^a, R Mohan Kumar ^a, P R Umarani ^b,^*, G Chakkaravarthi ^c,^*

PMCID: PMC4331910 PMID: 25705488

Abstract

In the title hydrated molecular salt, C₇H₁₁N₂ ⁺·C₇H₆NO₂ ⁻·2H₂O, the cation is protonated at the pyridine N atom and the dihedral angle between the benzene ring and the CO₂ ⁻ group in the anion is 8.5 (2)°. In the crystal, the cation forms an N—H⋯O hydrogen bond to the anion and the anion forms two N—H⋯O hydrogen bonds to adjacent water molecules. Both water molecules form two O—H⋯O hydrogen bonds to carboxylate O atoms. In combination, these hydrogen bonds generate a three-dimensional network and two weak C—H⋯π interactions are also observed.

Keywords: crystal structure, 4-(dimethylamino)pyridinium, 4-aminobenzoate, hydrate, hydrogen bonding

Related literature

For related structures, see: Dhanabalan et al. (2014 ▸); Lo & Ng (2008 ▸); Pereira Silva et al. (2010 ▸); Sivakumar et al. (2014 ▸). graphic file with name e-71-00o26-scheme1.jpg

Experimental

Crystal data

C₇H₁₁N₂ ⁺·C₇H₆NO₂ ⁻·2H₂O
M _r = 295.34
Triclinic,
a = 9.3402 (7) Å
b = 9.7999 (7) Å
c = 10.2132 (8) Å
α = 65.755 (3)°
β = 69.983 (2)°
γ = 89.212 (3)°
V = 792.08 (10) Å³
Z = 2
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 295 K
0.30 × 0.24 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▸) T _min = 0.973, T _max = 0.982
16983 measured reflections
3337 independent reflections
2141 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.054
wR(F ²) = 0.168
S = 1.03
3337 reflections
216 parameters
7 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.29 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▸); cell refinement: SAINT (Bruker, 2004 ▸); 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 ▸); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989014026310/hb7333sup1.cif

e-71-00o26-sup1.cif^{(24.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989014026310/hb7333Isup2.hkl

e-71-00o26-Isup2.hkl^{(160.3KB, hkl)}

Click here for additional data file.^{(6KB, cml)}

Supporting information file. DOI: 10.1107/S2056989014026310/hb7333Isup3.cml

Click here for additional data file.^{(1.1MB, tif)}

. DOI: 10.1107/S2056989014026310/hb7333fig1.tif

The molecular structure of (I), with 30% probability displacement ellipsoids for non-H atoms.

Click here for additional data file.^{(1.3MB, tif)}

a . DOI: 10.1107/S2056989014026310/hb7333fig2.tif

The packing of (I), viewed down a axis. Intermolecular Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted.

CCDC reference: 1036769

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (, ).

Cg2 is the centroid of the C1C6 benzene ring.

DHA	DH	HA	D A	DHA
N1H1AO3ⁱ	0.87(1)	2.04(1)	2.898(3)	167(2)
N1H1BO4ⁱ	0.89(1)	2.04(1)	2.921(3)	174(2)
N2H2AO1ⁱⁱ	0.89(1)	1.81(1)	2.697(2)	174(2)
O3H3AO2ⁱⁱⁱ	0.83(1)	2.03(1)	2.858(3)	175(4)
O3H3BO1^iv	0.83(1)	2.04(1)	2.861(3)	174(4)
O4H4AO2^v	0.82(1)	2.01(1)	2.834(3)	175(4)
O4H4BO1^vi	0.82(1)	2.04(1)	2.847(3)	167(4)
C9H9Cg2^vii	0.93	2.80	3.510(3)	134
C12H12Cg2ⁱ	0.93	2.84	3.535(3)	132

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .

Acknowledgments

The authors thank SAIF, IIT, Madras for thedata collection.

supplementary crystallographic information

S1. Chemical context

We hereby report the synthesis and crystal structure of the title compound (I), prepared by the reaction of 4-dimethylaminopyridine with 4-aminobenzoic acid in distilled water as solvent.

S2. Structural commentary

The geometric parameters of the title compound (I) (Fig.1) are comparable with the reported structures [Dhanabalan et al., 2014; Lo & Ng (2008); Pereira Silva et al., 2010; Sivakumar et al., 2014]. The 4-dimethylaminopyridinium cation is protonated at pyridine N2 atom, with the plane of the hetro atoms N(CH3)2 (N3/C13/C14) is inclined to the pyridine ring by 4.7 (2)°. In the 4-aminobenzoate anion, the plane of carboxylate group (C7/O1/O2) is skewed at an angle of 8.5 (2)° with the attached benzene ring (C1—C6). The dihedral angle between the benzene ring (C1—C6) and pyridine ring (N2/C8—C12) is 66.69 (8)°.

S3. Supramolecular features

In the crystal, the medium-strength N—H···O and O—H···O hydrogen bonds connect the adjacent anions and cations, involving water molecules into three dimensional framework (Table 2 & Fig. 2). The crystal structure also features weak C—H···π (Table 2) interactions.

S4. Synthesis and crystallization

4-Dimethylaminopyridine (C₇H₁₀N₂, 1.9704 g) and 4-aminobenzoic acid (C₇H₇NO₂, 2.2119 g) were taken in the equimolar ratio and synthesized in distilled water and prepared solution was allowed for slow evaporation at room temperature. Colourless blocks were collected after 20 days.

S5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The C-bound H atoms were positioned geometrically and refined using riding model, with C—H = 0.93 and 0.97 Å for CH_aromatic and CH₃, respectively, with U_iso(H) = 1.2Ueq(C) or 1.5Ueq(C). The H atoms bound to O and N atoms were found in a difference map and refined isotropically, with U_iso(H) = 1.5Ueq(O). The distance restraints O—H = 0.82 (1)Å and N—H = 0.88 (1)Å were applied during refinement.