4-(Ammonio­meth­yl)pyridinium dichloride

The title compound, C₆H₁₀N₂²⁺·2Cl⁻, contains a network of 4-(ammonio­meth­yl)pyridinium cations and chloride anions which are inter­connected by N—H...Cl hydrogen bonds. The crystal packing is also influenced by inter­molecular π–π stacking inter­actions between identical anti­parallel organic cations with a face-to-face distance of ca 3.52 Å.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.030
• wR factor = 0.030
• Data-to-parameter ratio = 17.7

checkCIF/PLATON results

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Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
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S1. Comment

The coordination chemistry of anions was the starting point for the development of new compounds having many practical and potential applications in various fields, such as supramolecular chemistry (Schmidtchen and Berger, 1997) and biochemical processes (Pajewski et al., 2004). Moreover, halide anions have been successfully used to assemble double-helical motifs of various molecules containing aromatic groups, with π-stacking interactions within the helices (Sessler et al., 2003). These anions can be useful for such applications because of the high flexibility of their coordination (Ilioudis et al., 2000). Here, a new member of this family, the title compound (C₆H₁₀Cl₂N₂), is presented, which has been obtained during our studies of the preparation of new organic hydrochloride compounds. As shown in Fig. 1, to ensure charge balance the organic species is doubly protonated at N1 and N2. Thus, the structure consists essentially of an 4-(ammoniomethyl)pyridinium cations and two Cl^- anions, associated in a hydrogen-bonded network. The Cl^- anions and the antiparallel pair of organic cations associate each other via hydrogen-bonding interactions to construct a convoluted hydrogen-bonded chain network which runs along the [111] direction at b = ¹/₂ (Fig. 3). This chain is made up by a four-membered donor-acceptor ring, involving two Cl atoms, fused along the N—H···Cl hydrogen bond (Fig. 2). These intermolecular hydrogen bonds generate edge-fussed [R₂⁴(8) and R₂⁴(20)] motifs (Bernstein et al., 1995). When viewed in perspective, the molecules chains have a marked zigzag structure and somewhat resembles a helix. As can be seen in Fig.2, the neighbouring pyridinyl rings run parallel in opposite directions and stack each other by turns in a face-to-face mode. The nearest centroid-centroid distance is 3.52 Å, less than 3.8 Å, a usually acceptad maximum value for π-π interactions (Jin et al., 2005). An examination of the organic moiety geometrical features shows that the atoms building the pyridinyl ring have a good coplanarity and they form a conjugated plane with average deviation of 0.005 Å). The mean value of C—C and N—C bond lengths are 1.381 (2) and 1.332 (2) Å) which are between that of a single bond and a double bond and agree with those in the literature (Oueslati et al., 2006). However, it is worth noticing that the C—N—C angles of pyridine are very sensitive to protonation (Krygowski et al., 2005). A pyridinium cation always possesses an expanded angle of C—N—C in comparison with the parent pyridine. The C1—N1—C5 angle [122.3 (2) °] is consistent with the type of pyridinium cation. In fact, the protonation of the nitrogen atom N1 decreases its electronegativity; hence the corresponding C—N—C angles becomes larger.

Related literature

For common applications of these complexes, see: Schmidtchen & Berger (1997); Pajewski et al. (2004); Sessler et al. (2003); Ilioudis et al. (2000). For structure cohesion, see: Bernstein et al. (1995); Jin et al. (2005). For discussion of C-N-C angle, see: Krygowski et al. (2005). For bond-length data, see: Oueslati <it> et al.</it> (2006).

S2. Experimental

An aqueous 1M HCl solution and 4-(amminomethyl)pyridine in a 2:1 molar ratio were mixed and dissolved in sufficient ethanol. Crystals of (I) grew as the ethanol evaporated at 293 K over the course of a few days.

S3. Refinement

The refinement was carried out with Iσ(I)>3 and a sinθ/λ>0.01 to get rid of the reflections in the vicinity of the beamstop. The refinement was thus carried out using 1609 reflections (out of the 1995 independent ones). The R value reported corresponds to the recomputed value with a 2σ cutoff (SHELX like).

The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H in the range 0.93–0.98, N—H in the range 0.86–0.89 and O—H = 0.82 Å) and U_iso(H) (in the range 1.2–1.5 times U_eq of the parent atom), after which the positions were refined with riding constraints.

Computing details

Data collection: CAD-4 EXPRESS (Straver, 1992); cell refinement: CAD-4 EXPRESS (Straver, 1992); data reduction: RC93 (Watkin et al., 1994); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures

	Fig. 1. A view of (I), showing 40% probability displacement ellipsoids and arbitrary spheres for the H atoms.
	Fig. 2. Crystal structure of C6H10Cl2N2 viewed along b axis showing that the molecules crystallize in a ring motif.
	Fig. 3. Perspective view of (I) showing four chains across the unit cell at b = 1/2 in the [111] direction

4-(Ammoniomethyl)pyridinium dichloride

Crystal data

C6H10N2^2+·2Cl^−	Z = 2
Mr = 181.06	F(000) = 188
Triclinic, P1	Dx = 1.456 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.257 (2) Å	Cell parameters from 25 reflections
b = 7.339 (3) Å	θ = 9–11°
c = 8.752 (1) Å	µ = 0.71 mm^−1
α = 79.14 (3)°	T = 293 K
β = 70.94 (4)°	Block, colorless
γ = 70.19 (3)°	0.16 × 0.15 × 0.12 mm
V = 412.9 (2) Å^3

Data collection

Enraf–Nonius CAD-4 diffractometer	θmax = 28.0°, θmin = 2.5°
Graphite monochromator	h = −9→9
ω/2θ scans	k = −9→9
3311 measured reflections	l = −5→11
1995 independent reflections	2 standard reflections every 400 reflections
1670 reflections with I > 2σ(I)	intensity decay: 4%
Rint = 0.014

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.030	H-atom parameters constrained
wR(F^2) = 0.030	[weight] = 1.0/[A0*T0(x) + A1*T1(x) ··· + An-1]*Tn-1(x)] where Ai are the Chebychev coefficients listed below and x = F /Fmax W = [weight] * [1-(deltaF/6*sigmaF)^2]^2 Ai are: 0.823 0.257 0.531
S = 1.06	(Δ/σ)max = 0.001
1609 reflections	Δρmax = 0.29 e Å^−3
91 parameters	Δρmin = −0.20 e Å^−3
0 restraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.36975 (6)	0.70916 (5)	0.85091 (4)	0.0357
Cl2	0.85118 (6)	0.60355 (5)	0.28807 (4)	0.0385
H1	0.6965	1.2683	0.3992	0.0408*
H2	0.7426	0.9613	0.4009	0.0420*
H3	0.7984	0.7600	0.6294	0.0385*
H4	0.7325	1.2354	0.8318	0.0427*
H5	0.6824	1.4162	0.5939	0.0458*
H6	0.7155	0.9365	1.0028	0.0427*
H7	0.9427	0.8393	0.9126	0.0426*
H8	0.6516	0.6757	0.9274	0.0509*
H9	0.8719	0.5860	0.8743	0.0510*
H10	0.7711	0.6183	1.0429	0.0511*
N1	0.71013 (19)	1.20012 (18)	0.48454 (13)	0.0347
N2	0.76974 (19)	0.66782 (17)	0.94222 (14)	0.0340
C1	0.7421 (2)	1.0097 (2)	0.49055 (16)	0.0330
C2	0.7738 (2)	0.8922 (2)	0.62759 (16)	0.0309
C3	0.76881 (19)	0.97525 (19)	0.76000 (15)	0.0263
C4	0.7352 (2)	1.1743 (2)	0.74770 (16)	0.0350
C5	0.7057 (3)	1.2852 (2)	0.60805 (18)	0.0401
C6	0.8048 (2)	0.8595 (2)	0.91467 (16)	0.0334

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0459 (2)	0.04261 (19)	0.02508 (16)	−0.01833 (15)	−0.01593 (13)	0.00223 (12)
Cl2	0.0537 (2)	0.03529 (18)	0.02893 (17)	−0.01461 (15)	−0.01409 (14)	−0.00186 (13)
N1	0.0390 (6)	0.0379 (6)	0.0203 (5)	−0.0065 (5)	−0.0087 (4)	0.0048 (4)
N2	0.0397 (6)	0.0337 (6)	0.0276 (5)	−0.0107 (5)	−0.0136 (5)	0.0062 (4)
C1	0.0371 (7)	0.0430 (8)	0.0218 (6)	−0.0148 (6)	−0.0090 (5)	−0.0036 (5)
C2	0.0393 (7)	0.0304 (6)	0.0266 (6)	−0.0136 (5)	−0.0116 (5)	−0.0011 (5)
C3	0.0265 (6)	0.0314 (6)	0.0214 (5)	−0.0101 (5)	−0.0071 (4)	0.0003 (5)
C4	0.0487 (8)	0.0343 (7)	0.0220 (6)	−0.0146 (6)	−0.0070 (6)	−0.0037 (5)
C5	0.0564 (9)	0.0271 (7)	0.0287 (7)	−0.0076 (6)	−0.0074 (6)	−0.0010 (5)
C6	0.0420 (7)	0.0359 (7)	0.0262 (6)	−0.0129 (6)	−0.0162 (5)	0.0024 (5)

Geometric parameters (Å, º)

H3—C2	0.923	H9—N2	0.899
H2—C1	0.919	N1—C1	1.331 (2)
H5—C5	0.909	N1—C5	1.333 (2)
H8—N2	0.890	N2—C6	1.4750 (19)
H7—C6	0.955	C6—C3	1.5065 (18)
H6—C6	0.961	C1—C2	1.3750 (19)
H1—N1	0.831	C3—C2	1.3929 (18)
H4—C4	0.923	C3—C4	1.386 (2)
H10—N2	0.890	C5—C4	1.371 (2)
H1—N1—C1	118.7	H2—C1—N1	117.8
H1—N1—C5	118.6	H2—C1—C2	122.2
C1—N1—C5	122.62 (12)	N1—C1—C2	120.03 (13)
H9—N2—H8	109.1	C6—C3—C2	123.50 (12)
H9—N2—H10	107.4	C6—C3—C4	117.95 (12)
H8—N2—H10	109.7	C2—C3—C4	118.52 (12)
H9—N2—C6	109.8	H5—C5—N1	116.9
H8—N2—C6	111.9	H5—C5—C4	123.6
H10—N2—C6	108.9	N1—C5—C4	119.51 (14)
N2—C6—H6	109.7	C3—C2—C1	119.26 (13)
N2—C6—H7	108.0	C3—C2—H3	121.6
H6—C6—H7	108.4	C1—C2—H3	119.2
N2—C6—C3	114.31 (11)	C3—C4—H4	121.5
H6—C6—C3	107.3	C3—C4—C5	120.05 (13)
H7—C6—C3	108.9	H4—C4—C5	118.4

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Cl1^i	0.83	2.36	3.084 (2)	146
N2—H8···Cl1	0.89	2.28	3.160 (3)	171
N2—H9···Cl2^ii	0.90	2.23	3.126 (2)	173
N2—H10···Cl2^iii	0.89	2.37	3.190 (2)	152

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