The charge-transfer complex 1-amino­anthraquinone–7,7′,8,8′-tetra­cyano­quinodimethane (1/1)

Adriano Bof de Oliveira; Johannes Beck; Jörg Daniels; Jaciara Nascimento Santos; Bárbara Regina Santos Feitosa

doi:10.1107/S1600536813002195

. 2013 Jan 26;69(Pt 2):o301. doi: 10.1107/S1600536813002195

The charge-transfer complex 1-aminoanthraquinone–7,7′,8,8′-tetracyanoquinodimethane (1/1)

Adriano Bof de Oliveira ^a,^*, Johannes Beck ^b, Jörg Daniels ^b, Jaciara Nascimento Santos ^a, Bárbara Regina Santos Feitosa ^a

PMCID: PMC3569820 PMID: 23424566

Abstract

The reaction of 1-aminoanthraquinone with 7,7′,8,8′-tetracyanoquinodimethane yielded the title charge-transfer complex, C₁₄H₉NO₂·C₁₂H₄N₄. The molecules have maximum deviations from the mean planes through the non-H atoms of 0.0769 (14) Å for an oxo O atom and 0.1175 (17) Å for a cyano N atom, respectively. The dihedral angle between the two planes is 3.55 (3)°. In the crystal, molecules are stacked into columns along the a-axis direction. Pairs of N—H⋯N and N—H⋯O interactions connect the molecules perpendicular to the stacking direction. Additionally, an intramolecular N—H⋯O hydrogen-bond interaction is observed for 1-aminoanthraquinone.

Related literature

For a revised structure of 1-aminoanthraquinone, see: Milić et al. (2012 ▶). For charge-transfer complexes of aromatic derivatives with 7,7′,8,8′-tetracyanoquinodimethane, see: Press et al. (2012 ▶). For the conductivity of organic salts, see: Jérome (2004 ▶). For the coordination chemistry of 7,7′,8,8′-tetracyanoquinodimethane, see: Kaim & Moscherosch (1994 ▶). graphic file with name e-69-0o301-scheme1.jpg

Experimental

Crystal data

C₁₂H₄N₄·C₁₄H₉NO₂
M _r = 427.41
Monoclinic,
a = 7.4916 (2) Å
b = 9.4321 (3) Å
c = 28.8093 (8) Å
β = 95.8785 (15)°
V = 2025.00 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.29 × 0.05 × 0.04 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: analytical (Alcock, 1970 ▶) T _min = 0.974, T _max = 0.996
19055 measured reflections
3972 independent reflections
2324 reflections with I > 2σ(I)
R _int = 0.147

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.135
S = 1.01
3972 reflections
350 parameters
All H-atom parameters refined
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Click here for additional data file.^{(21.9KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813002195/bt6884sup1.cif

e-69-0o301-sup1.cif^{(21.9KB, cif)}

Click here for additional data file.^{(194.7KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813002195/bt6884Isup2.hkl

e-69-0o301-Isup2.hkl^{(194.7KB, hkl)}

Click here for additional data file.^{(7.5KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813002195/bt6884Isup3.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—HN1⋯O2	0.93 (3)	1.96 (3)	2.654 (3)	130 (2)
N1—HN1⋯O2ⁱ	0.93 (3)	2.25 (3)	3.019 (3)	139 (2)
N1—HN2⋯N3ⁱⁱ	1.02 (3)	2.22 (3)	3.229 (3)	171 (2)

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

Acknowledgments

We gratefully acknowledge financial support by the German Research Foundation (DFG) through the Collaborative Research Center SFB 813, Chemistry at Spin Centers, and by FAPITEC/SE/FUNTEC/CNPq through the PPP Program 04/2011. JNS also acknowledges CAPES for the award of a scholarship.

supplementary crystallographic information

Comment

Charge transfer compounds with 7,7',8,8'-tetracyanoquinodimethane (TCNQ) as the acceptor component have a wide range of properties, such as paramagnetism, cooperative magnetism or electrical conductivity. TCNQ can be easily reduced to the anionic form. The single unpaired electron occupies the lowest unoccupied molecular orbitals, that are mainly located at the terminal dicyanomethylene fragments. When the TCNQ units stack and the intermolecular spacings are shorter than the van der Waals distances for carbon, the π orbitals will contribute to electrical conductivity (Jérome, 2004). Additionally, TCNQ compounds have a very interesting coordination chemistry (Kaim & Moscherosch, 1994). As part of our study of charge transfer complex structures, we report herein the synthesis and the crystal structure of a new TCNQ-acceptor compound with 1-aminoanthraquinone-donor (Milić et al., 2012).

In the title compound, the molecular structure unit matches the asymmetric unit (Fig. 1). Both molecules show only a slight deviation from planarity. The maximal deviation from the least squares plane through all non-hydrogen atoms for the 1-aminoanthraquinone and the 7,7',8,8'-tetracyanoquinodimethane molecule amount to 0.0769 (14) Å for O2 and 0.1175 (17) Å for N5, respectively, and the dihedral angle between the two planes is 3.55 (03)°. The bond angles suggest sp² hybridization for the C atoms and explain the planarity of both molecules. The structure is built from mixed stacks of donor and acceptor molecules. The stacks run the crystallographic a axis (Fig. 3). The mean distance between the molecules within the stack amounts to one half of the length of the a axis, i.e. 3.7456 (2) Å. This explains the low electrical conductivity of the compound. Above room temperature, however, a detectable electrical conductivity was observed, which reaches 4.4 × 10^-8 S/cm at 370 K. In the temperature range between 2 K and 300 K the title compound turned out as diamagnetic. The bond lengths within the dicyanomethylene groups suggest that the TCNQ units are neutral, comparing with crystal and infrared literature data (Kaim & Moscherosch, 1994). However, a small charge transfer is apparently present, since the electrical resistivity falls with increasing temperature indicating semiconducting characteristics. From the resistivity data, an Arrhenius development –ln(1/R) versus. 1/T gives a mainly linear behaviour, from which a small barrier for the thermally activated transport of 1.25 eV can be derived, according with dark brown colour of the crystals.

The crystal packing is stabilized by intermolecular hydrogen interactions. The molecules are connected by pairs of centrosymmetrical N—H···O and N—H···N hydrogen interactions, building dimers (Table 1; N1—HN1···O2ⁱ_; N1—HN2···N3ⁱⁱ and Fig. 2). Additionally, an intramolecular N—H···O hydrogen interaction is observed for the 1-aminoanthraquinone (Table 1; N1—HN1···O2 and Fig. 2).

Experimental

Starting materials were commercially available and were used without further purification. 1-Aminoanthraquinone and 7,7',8,8'-tetracyanoquinodimethane were dissolved in CH₂Cl₂ separately at room temperature and equimolar concentrations. The solutions were combined and maintained for 4 h under continuous stirring. Dark brown crystals, suitable for X-ray analysis, were obtained by the slow evaporation of the solvent. Elemental analysis: Calc. 73.1 C, 3.1 H, 16.4 N; found 72.8 C, 3.4 H, 16.6 N. The melting point was determined by differential scanning calorimetry to 520 K. Exothermic decomposition occurs at 555 K.