1-(3,4-Dichloro­benz­yl)-3-methyl­quinolin-1-ium 7,7,8,8-tetra­cyano­quinodimethanide

Guang-Xiang Liu; Chun-You Zhang

doi:10.1107/S1600536810002862

. 2010 Jan 30;66(Pt 2):o468. doi: 10.1107/S1600536810002862

1-(3,4-Dichlorobenzyl)-3-methylquinolin-1-ium 7,7,8,8-tetracyanoquinodimethanide

Guang-Xiang Liu ^a,^*, Chun-You Zhang ^a

PMCID: PMC2979894 PMID: 21579879

Abstract

In the title salt, C₁₇H₁₄Cl₂N⁺·C₁₂H₄N₄ ⁻, cations and anions stack along the a axis into segregated columns by π–π stacking interactions, with alternating centroid–centroid separations of 3.5957 (7) and 3.7525 (7) Å for the cation column and 3.4252 (6) and 4.1578 (7) Å for the anion column. In the cation, the dihedral angle between the benzene ring and the quinoline ring system is 76.35 (4)°. The crystal packing is stabilized by intercolumnar C—H⋯N hydrogen bonds.

Related literature

For general background to the planar organic molecule 7,7,8,8-tetracyanoquinodimethane, see: Alonso et al. (2005 ▶); Madalan et al. (2002 ▶); Liu et al. (2008 ▶). For the role played by the size and shape of the counter-cations in determining the ground-state properties of the resulting materials, see: Ren, Meng et al. (2002 ▶); Ren et al. (2003 ▶); Ren, Chen et al. (2002 ▶). For related structures, see: Liu et al. (2005 ▶).

Experimental

Crystal data

C₁₇H₁₄Cl₂N⁺·C₁₂H₄N₄ ⁻
M _r = 507.38
Monoclinic,
a = 7.0795 (14) Å
b = 18.704 (4) Å
c = 18.608 (4) Å
β = 95.286 (2)°
V = 2453.4 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.29 mm⁻¹
T = 293 K
0.26 × 0.16 × 0.12 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.928, T _max = 0.966
18184 measured reflections
4580 independent reflections
3680 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.101
S = 1.03
4580 reflections
326 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810002862/rz2411sup1.cif

e-66-0o468-sup1.cif^{(22.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810002862/rz2411Isup2.hkl

e-66-0o468-Isup2.hkl^{(224.4KB, 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
C20—H20⋯N3ⁱ	0.93	2.53	3.387 (3)	154
C19—H19B⋯N3ⁱ	0.97	2.51	3.432 (2)	158
C14—H14⋯N3ⁱⁱ	0.93	2.50	3.390 (3)	161
C15—H15⋯N1ⁱⁱⁱ	0.93	2.45	3.348 (2)	163

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 20971004), the Natural Science Foundation for Outstanding Scholars of Anhui Province, China (No. 044-J-04011) and the Outstanding Youth Foundation of the Education Commission of Anhui Province, China (No. 2010SQRL108ZD).

supplementary crystallographic information

Comment

The search for new compounds with promising electronic, and magnetic properties has prompted chemists to combine different spin carriers within the same molecular or supramolecular entity (Madalan et al., 2002). One of the most extensively used radicals in these studies has been the planar organic molecule 7,7,8,8-tetracyanoquinodimethane, [C₈H₄(CN)₄], TCNQ, since it shows a low reduction potential which makes it a suitable acceptor in charge-transfer processes. Another significant feature of this acceptor is its tendency to overlap its π-delocalized system with those of neighbouring molecules to form stacks with different degrees of electron delocalization (Alonso et al., 2005). Previous work has shown that molecular stacks of charge-transfer salts exhibit low-dimensional properties in some cases, which have intriguing anisotropic magnetic, electronic and structural characteristics (Ren, Meng et al., 2002; Ren et al., 2003; Liu et al., 2005). Furthermore, the size and shape of the counter-cations play an important role in determining the ground-state properties of the resulting materials (Ren, Chen et al., 2002; Liu et al., 2008). As a result, charge-transfer salts consisting of the TCNQ anion and benzylpyridinium cations could offer the possibility of systematically studying the fundamental relationship between the stack structure and the size and steric properties of substituent groups. In this communication, we report the crystal structure of the title complex.

The asymmetric unit of the title compound contains one (C₁₇H₁₄Cl₂N)⁺ cation and one [C₈H₄(CN)₄]^- anion (Fig. 1). Anions and cations stack into completely segregated columns along the a axis, as illustrated in Fig. 2. Within an anion column, the strongly bound unit [(TCNQ)₂]^2- is formed by π–π stacking interactions with a centroid-to-centroid distance of 3.4252 (6) Å, and adjacent units are displaced relative to each other along the direction of the shorter molecular axis of TCNQ with centroid-to-centroid separations of 4.1578 (7) Å (Fig. 3). Stacking within the cation column is also governed by π–π stacking interactions with alternating centroid-to-centroid distances 3.5957 (7) and 3.7525 (7) Å. The (C₁₇H₁₄Cl₂N)⁺ cation assumes a Λ-shaped conformation, with a dihedral angle between the benzene ring and the quinoline ring system of 76.35 (4)°. The crystal packing is stabilized by C—H···N intercolumar linkages (Table 1).

Experimental

1-(3,4-Dichlorobenzyl)-3-methylquinolin-1-ium iodide was prepared by the direct combination of 1:1 molar equivalents of 1-(3,4-dichlorobenzyl)-3-methylquinolin-1-ium chloride and NaI in a warm solution in acetone at 313 K. A white precipitate was formed (NaCl), which was filtered off, and a white microcrystalline product was obtained by evaporating the filtrate. 1:1 Molar equivalents of 1-(3,4-dichlorobenzyl)-3-methylquinolin-1-ium iodide and 7,7,8,8-tetracyanoquinodimethane (TCNQ) were mixed directly in methanol, and the mixture was refluxed for 12 h. The black microcrystalline product which formed was filtered off, washed with MeOH and dried in vacuo. Single crystals of the title compound suitable for X-ray structure analysis were obtained by diffusing diethyl ether into a MeCN solution.