(IUCr) Crystallography Journals Online

Abstract top

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-HO hydrogen bonds link individual pairs of cations and anions. The structure is further stabilized by an extensive series of C-HO hydrogen bonds, augmented by [pi] - [pi] [centroid-centroid distance between adjacent pyridinium rings = 3.5807 (10) Å] and C-H [pi] interactions, giving a network structure.

Comment top

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).

4-(Dimethylamino)pyridinium 4-toluenesulfonate top

Crystal data top

C₇H₁₁N₂⁺·C₇H₇O₃S^–	F₀₀₀ = 624
M_r = 294.36	D_x = 1.353 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 5199 reflections
a = 8.9878 (7) Å	θ = 2.3–28.4º
b = 17.5897 (12) Å	µ = 0.23 mm⁻¹
c = 9.8202 (6) Å	T = 91 (2) K
β = 111.429 (3)º	Block, colourless
V = 1445.18 (17) Å³	0.43 × 0.07 × 0.04 mm
Z = 4

Data collection top

Bruker APEXII CCD area-detector diffractometer	3792 independent reflections
Radiation source: fine-focus sealed tube	3087 reflections with I > 2σ(I)
Monochromator: graphite	R_int = 0.037
T = 91(2) K	θ_max = 28.9º
ω scans	θ_min = 2.7º
Absorption correction: multi-scan (SADABS; Bruker, 2006)	h = −12→11
T_min = 0.860, T_max = 0.991	k = −23→23
22414 measured reflections	l = −13→13

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.042	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.125	w = 1/[σ²(F_o²) + (0.0662P)² + 0.7048P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max = 0.001
3792 reflections	Δρ_max = 1.11 e Å⁻³
188 parameters	Δρ_min = −0.40 e Å⁻³
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Crystal data top

C₇H₁₁N₂⁺·C₇H₇O₃S^–	V = 1445.18 (17) Å³
M_r = 294.36	Z = 4
Monoclinic, P2₁/n	Mo Kα
a = 8.9878 (7) Å	µ = 0.23 mm⁻¹
b = 17.5897 (12) Å	T = 91 (2) K
c = 9.8202 (6) Å	0.43 × 0.07 × 0.04 mm
β = 111.429 (3)º

Data collection top

Bruker APEXII CCD area-detector diffractometer	3792 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2006)	3087 reflections with I > 2σ(I)
T_min = 0.860, T_max = 0.991	R_int = 0.037
22414 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	188 parameters
wR(F²) = 0.125	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 1.11 e Å⁻³
3792 reflections	Δρ_min = −0.40 e Å⁻³

Special details top

Experimental. As the crystals were weakly diffracting data was collected using 55 sec exposures per frame.
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.

Experimental. As the crystals were weakly diffracting data was collected using 55 sec exposures per frame.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
S1	0.62942 (4)	0.40655 (2)	0.30685 (4)	0.02071 (12)
O1	0.65251 (15)	0.46441 (8)	0.41760 (13)	0.0300 (3)
O2	0.76431 (14)	0.35591 (8)	0.33293 (14)	0.0305 (3)
O3	0.57456 (14)	0.43952 (7)	0.15893 (12)	0.0253 (3)
C1	0.46612 (19)	0.35035 (9)	0.30817 (17)	0.0218 (3)
C2	0.4183 (2)	0.28743 (10)	0.21659 (18)	0.0262 (3)
H2	0.4773	0.2724	0.1582	0.031*
C3	0.2834 (2)	0.24663 (10)	0.2110 (2)	0.0320 (4)
H3	0.2503	0.2040	0.1477	0.038*
C4	0.1961 (2)	0.26748 (11)	0.2972 (2)	0.0338 (4)
C5	0.2470 (2)	0.32962 (12)	0.3887 (2)	0.0336 (4)
H5	0.1893	0.3440	0.4487	0.040*
C6	0.3805 (2)	0.37166 (11)	0.39512 (18)	0.0275 (4)
H6	0.4129	0.4145	0.4581	0.033*
C7	0.0465 (3)	0.22552 (14)	0.2912 (3)	0.0531 (6)
H7A	−0.0405	0.2620	0.2757	0.080*
H7B	0.0674	0.1985	0.3835	0.080*
H7C	0.0160	0.1889	0.2103	0.080*
N1	0.24038 (18)	0.56935 (9)	0.00587 (17)	0.0267 (3)
H1	0.301 (3)	0.5637 (13)	−0.037 (2)	0.036 (6)*
C8	0.2816 (2)	0.54668 (9)	0.14560 (19)	0.0250 (3)
H8	0.3848	0.5256	0.1948	0.030*
C9	0.17879 (18)	0.55323 (9)	0.21827 (17)	0.0207 (3)
H9	0.2105	0.5373	0.3173	0.025*
C10	0.02343 (18)	0.58410 (8)	0.14474 (16)	0.0172 (3)
C11	−0.0123 (2)	0.60940 (9)	−0.00116 (17)	0.0211 (3)
H11	−0.1129	0.6322	−0.0537	0.025*
C12	0.0971 (2)	0.60106 (10)	−0.06569 (18)	0.0254 (3)
H12	0.0717	0.6180	−0.1634	0.031*
N2	−0.08300 (16)	0.58856 (8)	0.21026 (14)	0.0206 (3)
C13	−0.0458 (2)	0.55874 (11)	0.35772 (17)	0.0280 (4)
H13A	0.0303	0.5927	0.4286	0.042*
H13B	0.0013	0.5080	0.3647	0.042*
H13C	−0.1441	0.5556	0.3789	0.042*
C14	−0.2376 (2)	0.62548 (12)	0.13823 (19)	0.0296 (4)
H14A	−0.2949	0.6003	0.0447	0.044*
H14B	−0.2210	0.6791	0.1208	0.044*
H14C	−0.3008	0.6218	0.2009	0.044*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.01460 (19)	0.0296 (2)	0.01777 (19)	0.00256 (14)	0.00579 (14)	0.00122 (14)
O1	0.0244 (6)	0.0395 (7)	0.0268 (6)	−0.0059 (5)	0.0103 (5)	−0.0087 (5)
O2	0.0181 (6)	0.0409 (7)	0.0314 (6)	0.0095 (5)	0.0077 (5)	0.0044 (5)
O3	0.0191 (6)	0.0375 (7)	0.0220 (6)	0.0038 (5)	0.0107 (4)	0.0071 (5)
C1	0.0185 (7)	0.0270 (8)	0.0187 (7)	0.0030 (6)	0.0052 (6)	0.0067 (6)
C2	0.0254 (8)	0.0247 (8)	0.0262 (8)	0.0076 (7)	0.0069 (6)	0.0069 (6)
C3	0.0305 (9)	0.0217 (8)	0.0368 (10)	0.0022 (7)	0.0040 (8)	0.0065 (7)
C4	0.0253 (9)	0.0304 (9)	0.0448 (11)	0.0019 (7)	0.0118 (8)	0.0155 (8)
C5	0.0282 (9)	0.0409 (11)	0.0368 (10)	0.0026 (8)	0.0181 (8)	0.0090 (8)
C6	0.0244 (8)	0.0359 (10)	0.0235 (8)	0.0010 (7)	0.0102 (7)	0.0030 (7)
C7	0.0366 (12)	0.0412 (12)	0.0846 (19)	0.0004 (9)	0.0258 (12)	0.0119 (12)
N1	0.0268 (7)	0.0282 (8)	0.0331 (8)	−0.0029 (6)	0.0205 (6)	−0.0057 (6)
C8	0.0209 (8)	0.0213 (8)	0.0347 (9)	0.0010 (6)	0.0126 (7)	−0.0004 (7)
C9	0.0189 (7)	0.0191 (7)	0.0229 (7)	0.0016 (6)	0.0064 (6)	0.0018 (6)
C10	0.0183 (7)	0.0161 (7)	0.0172 (7)	−0.0013 (5)	0.0067 (5)	−0.0020 (5)
C11	0.0224 (8)	0.0230 (8)	0.0176 (7)	0.0009 (6)	0.0070 (6)	0.0008 (6)
C12	0.0295 (9)	0.0285 (9)	0.0208 (7)	−0.0042 (7)	0.0121 (6)	−0.0021 (6)
N2	0.0173 (6)	0.0286 (7)	0.0164 (6)	0.0026 (5)	0.0067 (5)	0.0020 (5)
C13	0.0232 (8)	0.0437 (10)	0.0184 (7)	0.0004 (7)	0.0093 (6)	0.0057 (7)
C14	0.0185 (8)	0.0445 (10)	0.0259 (8)	0.0094 (7)	0.0082 (6)	0.0047 (7)

Geometric parameters (Å, °) top

S1—O1	1.4481 (13)	N1—C8	1.344 (2)
S1—O2	1.4499 (12)	N1—H1	0.81 (2)
S1—O3	1.4718 (11)	C8—C9	1.363 (2)
S1—C1	1.7735 (17)	C8—H8	0.9500
C1—C2	1.391 (2)	C9—C10	1.425 (2)
C1—C6	1.394 (2)	C9—H9	0.9500
C2—C3	1.392 (3)	C10—N2	1.3360 (19)
C2—H2	0.9500	C10—C11	1.420 (2)
C3—C4	1.397 (3)	C11—C12	1.359 (2)
C3—H3	0.9500	C11—H11	0.9500
C4—C5	1.382 (3)	C12—H12	0.9500
C4—C7	1.515 (3)	N2—C13	1.4595 (19)
C5—C6	1.391 (3)	N2—C14	1.461 (2)
C5—H5	0.9500	C13—H13A	0.9800
C6—H6	0.9500	C13—H13B	0.9800
C7—H7A	0.9800	C13—H13C	0.9800
C7—H7B	0.9800	C14—H14A	0.9800
C7—H7C	0.9800	C14—H14B	0.9800
N1—C12	1.342 (2)	C14—H14C	0.9800

O1—S1—O2	114.71 (8)	C8—N1—H1	120.4 (16)
O1—S1—O3	111.64 (8)	N1—C8—C9	121.48 (16)
O2—S1—O3	111.92 (7)	N1—C8—H8	119.3
O1—S1—C1	106.15 (8)	C9—C8—H8	119.3
O2—S1—C1	107.29 (8)	C8—C9—C10	119.56 (15)
O3—S1—C1	104.31 (7)	C8—C9—H9	120.2
C2—C1—C6	120.03 (16)	C10—C9—H9	120.2
C2—C1—S1	119.99 (13)	N2—C10—C11	121.97 (14)
C6—C1—S1	119.89 (14)	N2—C10—C9	121.33 (14)
C1—C2—C3	119.64 (16)	C11—C10—C9	116.70 (14)
C1—C2—H2	120.2	C12—C11—C10	120.08 (15)
C3—C2—H2	120.2	C12—C11—H11	120.0
C2—C3—C4	120.97 (18)	C10—C11—H11	120.0
C2—C3—H3	119.5	N1—C12—C11	121.34 (15)
C4—C3—H3	119.5	N1—C12—H12	119.3
C5—C4—C3	118.39 (17)	C11—C12—H12	119.3
C5—C4—C7	119.3 (2)	C10—N2—C13	120.79 (13)
C3—C4—C7	122.3 (2)	C10—N2—C14	120.98 (13)
C4—C5—C6	121.65 (17)	C13—N2—C14	118.20 (13)
C4—C5—H5	119.2	N2—C13—H13A	109.5
C6—C5—H5	119.2	N2—C13—H13B	109.5
C5—C6—C1	119.31 (17)	H13A—C13—H13B	109.5
C5—C6—H6	120.3	N2—C13—H13C	109.5
C1—C6—H6	120.3	H13A—C13—H13C	109.5
C4—C7—H7A	109.5	H13B—C13—H13C	109.5
C4—C7—H7B	109.5	N2—C14—H14A	109.5
H7A—C7—H7B	109.5	N2—C14—H14B	109.5
C4—C7—H7C	109.5	H14A—C14—H14B	109.5
H7A—C7—H7C	109.5	N2—C14—H14C	109.5
H7B—C7—H7C	109.5	H14A—C14—H14C	109.5
C12—N1—C8	120.78 (14)	H14B—C14—H14C	109.5
C12—N1—H1	118.9 (16)

O1—S1—C1—C2	−177.44 (13)	C2—C1—C6—C5	−0.3 (2)
O2—S1—C1—C2	−54.35 (14)	S1—C1—C6—C5	176.27 (13)
O3—S1—C1—C2	64.53 (14)	C12—N1—C8—C9	1.7 (3)
O1—S1—C1—C6	6.04 (15)	N1—C8—C9—C10	0.6 (2)
O2—S1—C1—C6	129.12 (14)	C8—C9—C10—N2	177.23 (15)
O3—S1—C1—C6	−112.00 (14)	C8—C9—C10—C11	−2.5 (2)
C6—C1—C2—C3	0.8 (2)	N2—C10—C11—C12	−177.39 (15)
S1—C1—C2—C3	−175.68 (12)	C9—C10—C11—C12	2.3 (2)
C1—C2—C3—C4	−0.6 (3)	C8—N1—C12—C11	−1.8 (3)
C2—C3—C4—C5	−0.2 (3)	C10—C11—C12—N1	−0.2 (3)
C2—C3—C4—C7	178.49 (18)	C11—C10—N2—C13	176.99 (15)
C3—C4—C5—C6	0.8 (3)	C9—C10—N2—C13	−2.7 (2)
C7—C4—C5—C6	−177.93 (19)	C11—C10—N2—C14	−4.9 (2)
C4—C5—C6—C1	−0.6 (3)	C9—C10—N2—C14	175.34 (15)

Hydrogen-bond geometry (Å, °) top

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

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+1; (iv) −x, −y+1, −z; (v) x+1/2, −y+1/2, z+1/2.

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

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

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+1; (iv) −x, −y+1, −z; (v) x+1/2, −y+1/2, z+1/2.

supplementary materials

4-(Dimethylamino)pyridinium 4-toluenesulfonate

C. J. McAdam and J. Simpson

	Fig. 1. The asymmetric unit of (I), with atom labels and 50% probability displacement ellipsoids for non-H atoms.
	Fig. 2. Crystal packing of (I) with hydrogen bonds drawn as dashed lines.
	Fig. 3. π···π stacking (dotted lines) between adjacent pyridinium rings of (I). The red circles represent pyridinium ring centroids separated by 3.5807 (10) Å. Additional hydrogen bonding interactions are shown as dashed lines.