A triclinic polymorph of 4-cyano­pyridinium hydrogen chloranilate

Kazuma Gotoh; Hiroyuki Ishida

doi:10.1107/S1600536812037221

. 2012 Sep 1;68(Pt 10):o2830. doi: 10.1107/S1600536812037221

A triclinic polymorph of 4-cyanopyridinium hydrogen chloranilate

Kazuma Gotoh ^a, Hiroyuki Ishida ^a,^*

PMCID: PMC3470192 PMID: 23125636

Abstract

The asymmetric unit of the triclinic polymorph of the title compound (systematic name: 4-cyanopyridinium 2,5-dichloro-4-hydroxy-3,6-dioxocyclohexa-1,4-dien-1-olate), C₆H₅N₂ ⁺·C₆HCl₂O₄ ⁻, consists of two crystallographically independent cation–anion units, in each of which the cation and the anion are linked by an N—H⋯O hydrogen bond. In the units, the dihedral angles between the cation and anion rings are 78.43 (11) and 80.71 (11)°. In the crystal, each unit independently forms a chain through N—H⋯O and O—H⋯N hydrogen bonds; one chain runs along the c axis while the other runs along [011]. Weak C—H⋯O, C—H⋯N and C—H⋯Cl interactions are observed between the chains.

Related literature

For the monoclinic polymorph, see: Tomura & Yamashita (2008 ▶); Gotoh et al. (2008 ▶). For hydrogen-bonding patterns in chloranilic acid–organic base (1/1) systems, see: Ishida & Kashino (2002 ▶). For ³⁵Cl nuclear quadrupole resonance studies on proton transfer in chloranilic acid–organic base systems, see: Nihei et al. (2000 ▶).

Experimental

Crystal data

C₆H₅N₂ ⁺·C₆HCl₂O₄ ⁻
M _r = 313.10
Triclinic,
a = 9.3918 (7) Å
b = 10.6652 (7) Å
c = 13.9135 (8) Å
α = 111.8033 (18)°
β = 106.258 (3)°
γ = 90.416 (3)°
V = 1232.50 (14) Å³
Z = 4
Mo Kα radiation
μ = 0.54 mm⁻¹
T = 180 K
0.36 × 0.31 × 0.09 mm

Data collection

Rigaku R-AXIS RAPID II diffractometer
Absorption correction: numerical (NUMABS; Higashi, 1999 ▶) T _min = 0.866, T _max = 0.953
21354 measured reflections
7135 independent reflections
4934 reflections with I > 2σ(I)
R _int = 0.108

Refinement

R[F ² > 2σ(F ²)] = 0.066
wR(F ²) = 0.164
S = 0.99
7135 reflections
377 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.89 e Å⁻³
Δρ_min = −0.83 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku/MSC, 2004 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812037221/lh5521sup1.cif

e-68-o2830-sup1.cif^{(30KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812037221/lh5521Isup2.hkl

e-68-o2830-Isup2.hkl^{(349.1KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812037221/lh5521Isup3.cml

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
N1—H1⋯O2	0.95 (4)	1.67 (4)	2.602 (2)	170 (3)
N3—H3⋯O6	0.90 (4)	1.84 (4)	2.719 (3)	166 (3)
O4—H4⋯N2ⁱ	0.80 (4)	1.99 (4)	2.741 (3)	155 (4)
O8—H8⋯N4ⁱⁱ	0.93 (5)	2.07 (5)	2.875 (3)	144 (4)
C13—H13⋯N4ⁱⁱⁱ	0.95	2.55	3.407 (3)	150
C14—H14⋯O3^iv	0.95	2.42	3.209 (3)	141
C16—H16⋯Cl3^v	0.95	2.71	3.431 (3)	133
C17—H17⋯O1^vi	0.95	2.30	3.194 (3)	157
C19—H19⋯O2	0.95	2.25	3.192 (3)	170
C20—H20⋯Cl1	0.95	2.83	3.626 (3)	142
C23—H23⋯O5^vii	0.95	2.14	3.040 (3)	158

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

Acknowledgments

This work was supported by a Grant-in-Aid for Scientific Research (C) (No. 22550013) from the Japan Society for the Promotion of Science.

supplementary crystallographic information

Comment

The title compound was accidentally obtained in the preparation of the monoclinic polymorph of 4-cyanopyridinium chloranilate, C₆H₅N₂⁺.C₆HCl₂O₄^-, which is an interesting model compound for investigating proton transfer in the hydrogen bond systems (Nihei et al., 2000). The structure of the monoclinic polymorph has been reported by Tomura & Yamashita (2008) and Gotoh et al. (2008).

The asymmetric unit of the triclinic polymorph of the title compound consists of two crystallographically independent cation–anion units, in each of which the cation and the anion are held together by N—H···O hydrogen bond. The dihedral angle between the N1/C13–C17 pyridine ring and the C1–C6 of the acid ring is 78.43 (11)° in one unit, while the angle between the N3/C19–C23 and C7–C12 rings is 80.71 (11)° in the other unit.

In the crystal structure of the monoclinic polymorph, the acid molecule (A) and the base molecule (B) afford an centrosymmetric 2:2 (B:A:A:B) aggregate (Ishida & Kashino, 2002) through O—H···O and N···H···O hydrogen bonds and the H atom in the N···H···O hydrogen bond is disordered over two positions (Gotoh et al., 2008). In contrast to the monoclinic form, the present triclinic polymorph shows two crystallographically independent 1:1 (A:B) units of the acid and base molecules. Each unit independently forms a hydrogen-bonded (–A:B:A:B–) chain; one chain formed by N1—H1···O2 and O4—H4···N2ⁱ (symmetry code in Table 1) hydrogen bonds runs along the c axis, while the other chain formed by N3—H3···O6 and O8—H8···N4ⁱⁱ (symmetry code in Table 1) hydrogen bonds runs along the [011] direction. No H atom disorder is observed in these hydrogen bonds. Between the chains, C—H···O, C—H···N and C—H···Cl interactions (Table 1) are observed.

Experimental

Single crystals were obtained by slow evaporation from an acetonitrile solution (130 ml) of chloranilic acid (0.60 g) and 4-cyanopyridine (0.30 g) at room temperature.