4-(Dimethyl­amino)pyridinium 4-toluene­sulfonate

C John McAdam; Jim Simpson

doi:10.1107/S1600536808004856

. 2008 Feb 27;64(Pt 3):o627–o628. doi: 10.1107/S1600536808004856

4-(Dimethylamino)pyridinium 4-toluenesulfonate

C John McAdam ^a, Jim Simpson ^a,^*

PMCID: PMC2960775 PMID: 21201959

Abstract

In the title compound, C₇H₁₁N₂ ⁺·C₇H₇O₃S⁻, the cation is protonated at the N atom of the heterocyclic ring. The dimethylamino group lies close to the pyridinium ring plane with a dihedral angle between the pyridinium and the dimethylamine CNC planes of 3.82 (17)°. The N—C bond linking the dimethylamino substituent to the pyridinium ring is characteristically short [1.3360 (19) Å], suggesting some delocalization in the cation. In the crystal structure, N—H⋯O hydrogen bonds link individual pairs of cations and anions. The structure is further stabilized by an extensive series of C—H⋯O hydrogen bonds, augmented by π–π [centroid–centroid distance between adjacent pyridinium rings = 3.5807 (10) Å] and C—H⋯π interactions, giving a network structure.

Related literature

For the preparation and uses of the title compound, see: Haynes & Indorato (1984 ▶); Moore, & Stupp (1990 ▶). For structures having the 4-(dimethylamino)pyridinium cation, see for example: Chao et al. (1977 ▶); Mayr-Stein & Bolte (2000 ▶); Sluka et al. (2003 ▶). For structures of salts of the 4-toluenesulfonate anion with pyridinium or similar cations, see for example: Koshima et al. (2001 ▶, 2004 ▶); Biradha & Mahata (2005 ▶). For details of the Cambridge structural database, see: Allen (2002 ▶).

Experimental

Crystal data

C₇H₁₁N₂ ⁺·C₇H₇O₃S⁻
M _r = 294.36
Monoclinic,
a = 8.9878 (7) Å
b = 17.5897 (12) Å
c = 9.8202 (6) Å
β = 111.429 (3)°
V = 1445.18 (17) Å³
Z = 4
Mo Kα radiation
μ = 0.23 mm⁻¹
T = 91 (2) K
0.43 × 0.07 × 0.04 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.860, T _max = 0.991
22414 measured reflections
3792 independent reflections
3087 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.125
S = 1.05
3792 reflections
188 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.11 e Å⁻³
Δρ_min = −0.41 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: APEX2 and SAINT (Bruker, 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶) and TITAN2000 (Hunter & Simpson, 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and TITAN2000; molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97, enCIFer (Allen et al., 2004 ▶) and PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808004856/ng2425sup1.cif

e-64-0o627-sup1.cif^{(17.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808004856/ng2425Isup2.hkl

e-64-0o627-Isup2.hkl^{(185.9KB, 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
C8—H8⋯O3	0.95	2.40	3.201 (2)	142
N1—H1⋯O3ⁱ	0.81 (2)	1.92 (2)	2.7160 (18)	171 (2)
C12—H12⋯O2ⁱ	0.95	2.64	3.376 (2)	135
C7—H7A⋯O2ⁱⁱ	0.98	2.62	3.553 (3)	160
C13—H13C⋯O1ⁱⁱ	0.98	2.56	3.408 (2)	145
C6—H6⋯O1ⁱⁱⁱ	0.95	2.63	3.490 (2)	151
C9—H9⋯O1ⁱⁱⁱ	0.95	2.44	3.350 (2)	160
C13—H13A⋯O2ⁱⁱⁱ	0.98	2.56	3.502 (2)	161
C14—H14A⋯O3^iv	0.98	2.67	3.541 (2)	148
C11—H11⋯Cg2^v	0.95	2.72	3.5883 (18)	152

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) . Cg2 is the centroids of the C1–C6 ring.

Acknowledgments

We thank the New Zealand Foundation for Research Science and Technology for a Postdoctoral Fellowship to CJM and the University of Otago for the purchase of the diffractometer.

supplementary crystallographic information

Comment

The title compound (I) was first reported and characterized as a side product by Haynes and Indorato (1984). However, it is better known under the acronym DPTS following the work of Moore and Stupp (1990) for its role as a convenient provider of stoichiometric quantities of anhydrous p-toluenesulfonic acid (PTSA) and 4-(dimethylamino)pyridine (DMAP) for the catalytic synthesis of polyesters at room temperature. Our interest in the synthesis of organometallic polyesters required the synthesis of DPTS and its structure is reported here, Fig 1.

The asymmetric unit of (I), C₇H₁₁N₂⁺, C₇H₇O₃S^-, consists of a 4-(dimethylamino)pyridinium cation and a 4-toluenesulfonate anion. In common with other DMAPH⁺ cations (Chao et al., 1977; Mayr-Stein & Bolte, 2000; Sluka et al., 2003), protonation is at the N1 atom of the pyridinium ring. Bond distances and angles in both the cation and anion are normal (Allen et al., 1987) and those in the anion are comparable to those in other 4-toluenesulfonate salts (Koshima et al., 2001, 2004; Biradha & Mahata 2005). The N2—C10 bond linking the dimethylamino substituent to the pyridinium ring is short, 1.3360 (19)Å suggesting some delocalization in the cation. The fact that the dimethylamino group lies close to the plane of the pyridinium ring, with a dihedral between the pyridinium and the dimethylamine C13N2C14 planes of 3.82 (17)°, supports this observation as does the fact that the C10N2C13C14 system is reasonably planar with an r.m.s. deviation of 0.006 Å. A search of the Cambridge structural database (Allen, 2002) reveals 47 similar structures incorporating the 4-(dimethylamino)pyridinium cation for which the mean corresponding N—C distance is 1.34 (1) Å.

In the crystal structure N—H···O hydrogen bonds link individual pairs of cations and anions and the structure is further stabilized by an extensive network of C—H···O hydrogen bonds, Fig. 2, Table 1. In addition π···π stacking beween adjacent pyridinium rings (Cg1···Cg1 = 3.5807 (10) Å), Fig. 3, and C11—H11···Cg2 interactions also contribute to the crystal packing. (Cg1 & Cg2 are the centroids of the N1, C8···C12 and C1···C6 rings respectively).

Experimental

The title compound was prepared according to the method of Moore and Stupp (1990) with X-ray quality crystals grown from 1,2-dichloroethane.