1,4-Dihydro­benzo[g]quinoxaline-2,3-dione

François Eya’ane Meva; Dieter Schaarschmidt; Mohammad A Abdulmalic; Tobias Rüffer

doi:10.1107/S1600536812047526

. 2012 Nov 28;68(Pt 12):o3460–o3461. doi: 10.1107/S1600536812047526

1,4-Dihydrobenzo[g]quinoxaline-2,3-dione

François Eya’ane Meva ^a,^*, Dieter Schaarschmidt ^b, Mohammad A Abdulmalic ^b, Tobias Rüffer ^b

PMCID: PMC3589036 PMID: 23476272

Abstract

The title compound, C₁₂H₈N₂O₂, was prepared by the reaction of the diethyl ester of naphthalenebis(oxamate) with tert-BuNH₂. The molecule is nearly planar, with an r.m.s. deviation of 0.017 Å from the plane through all 16 non-H atoms. In the crystal, a three-dimensional network is formed, composed of layers of molecules along the b- and c-axis directions, due to the formation of intermolecular N—H⋯O hydrogen bonds, as well as of chains along the a-axis direction due to parallel displaced sandwich-type π–π interactions with average distances between the interacting molecules in the range 3.35–3.40 Å.

Related literature

For the synthesis and structure of 1,4-dihydrobenzo[g]quinoxaline-2,3-dione·3H₂O, see: Oxtoby et al. (2005 ▶). For the use of bis(oxamates) and bis(oxamidates) for complex formation, see: Pardo et al. (2008 ▶) and Abdulmalic et al. (2012 ▶); Rüffer et al. (2012 ▶), respectively. For the general synthesis of bis(oxamidates), see: Ruiz et al. (1997 ▶) and for the synthesis of diethyl N,N’-naphtalene-bis(oxamate), see: Rüffer et al. (2007 ▶). For thin film formation by bis(oxamato) complexes, see: Eya’ane Meva (2009 ▶); Bräuer et al. (2006 ▶). For self-organization in supramolecular chemistry due to intermolecular π interactions and/or hydrogen bonds, see: Burrow et al. (1996 ▶); Chowdhry et al. (1996 ▶); Dai et al. (1997 ▶); Munoz et al. (1998 ▶). For dione tautomerism in the solid state, see: Svenson (1976 ▶).

Experimental

Crystal data

C₁₂H₈N₂O₂
M _r = 212.20
Monoclinic,
a = 7.1334 (15) Å
b = 8.4229 (18) Å
c = 15.292 (2) Å
β = 99.792 (14)°
V = 905.4 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 293 K
0.3 × 0.2 × 0.1 mm

Data collection

Oxford Gemini S diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006 ▶) T _min = 0.649, T _max = 1.000
5294 measured reflections
1773 independent reflections
875 reflections with I > 2σ(I)
R _int = 0.039

Refinement

R[F ² > 2σ(F ²)] = 0.094
wR(F ²) = 0.271
S = 0.92
1773 reflections
153 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.77 e Å⁻³
Δρ_min = −0.57 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 ▶); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶); software used to prepare material for publication: WinGX (Farrugia, 2012 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Click here for additional data file.^{(21.4KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812047526/sj5284sup1.cif

e-68-o3460-sup1.cif^{(21.4KB, cif)}

Click here for additional data file.^{(85.5KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812047526/sj5284Isup3.hkl

e-68-o3460-Isup3.hkl^{(85.5KB, hkl)}

Click here for additional data file.^{(4.1KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812047526/sj5284Isup3.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—H1N⋯O1ⁱ	0.91 (4)	2.27 (4)	2.866 (3)	122 (3)
N2—H2N⋯O2ⁱⁱ	0.94 (4)	1.90 (4)	2.843 (4)	176 (4)

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

Acknowledgments

FEM and MAA are grateful to the DAAD for PhD research fellowships and the DFG research unit "Towards Molecular Spintronics" FOR 1154 for providing fellowships. The authors express sincere thanks to the CIM, WUS, and the Faculty of Medicine and Pharmaceutical Sciences of the University of Douala for financial support.

supplementary crystallographic information

Comment

Weak interactions such as intermolecular π interactions or the formation of hydrogen bonds are essential for molecular recognition and self organization in biological systems and supramolecular chemistry (Burrow et al., 1996; Chowdhry et al., 1996; Dai et al., 1997). Oxtoby et al. (2005) synthesized derivatives of dihydroquinoxalinedione containing a hydrophilic oxalamide-based "terminus". This oxalamide serves to increase the water solubility of the organic molecules and allows H₂O molecules to be hydrogen bonded to the organic molecules as well as to each other. In this perspective, 1,4 dihydrobenzo[g]quinoxaline-2,3-dione hydrate (1×3H₂O) has been crystallized by slowly cooling a boiling solution of the powder in DMF/water to room temperature (Oxtoby et al., 2005). Infinite arrays containing two different alternating head-to-tail π interactions parallel to the crystallographic a axis were observed in the solid state of 1×3H₂O, with the π stacks being orthogonal to chains of H₂O molecules and held together by R²₂(8) hydrogen-bonding interactions.

Bis(oxamate) molecules (type I molecules, cf. Figure 4) have been widely used in order to produce a series of complexes with various magnetic interactions (Pardo et al., 2008). In previous work, our interest was devoted to a study of the impact of π interactions in the formation of thin films using trimetallic bis(oxamato) type complexes (Eya'ane Meva, 2009; Bräuer et al., 2006) as well as the investigation of electronic effects on magnetic J couplings (Rüffer et al., 2007). With the aim of using type I—NR₂ molecules as ligands for the formation of transition metal complexes (Abdulmalic et al., 2012; Rüffer et al., 2012), we became interested in their synthesis. Generally, type I molecules are reacted with an excess of a primary amine (Ruiz et al., 1997) resulting in the formation of type I—NR₂ molecules. On the other hand, quinoxaline derivatives are generally synthesized by refluxing diamines and oxalic acid in HCl (Oxtoby et al., 2005). We report here, that the reaction of the diethyl ester of naphtalene-bis(oxamate) (Rüffer et al., 2007), Fig. 4, with an excess of tert-BuNH₂ in MeOH does not give the corresponding type I—NR₂ molecule, but instead forms 1,4-dihydrobenzo[g]quinoxaline-2,3-dione (1). A similar reaction has been already described by Munoz et al. (1998), who treated o-phenylenebis(oxamate) with [Me₄N]OH and Fe(ClO₄)₃ to obtain an analogous derivatized product in the form of its Fe(III) complex.

In the solid state 1 is nearly planar (r. m. s. d. of a calculated mean plane of C1–C12, O1, O2, N1, N2 = 0.017 Å). The bond lengths of the C═O functions of 1 (1.230 (4) and 1.240 (4) Å) reveal the molecule to be the dione tautomer in the solid state (Svenson, 1976). All other bond distances and angles are comparable those described for 1×3H₂O (Oxtoby et al., 2005).

In the crystal structure of 1 the formation of a three-dimensional network is observed. Intermolecular hydrogen bonds between individual molecules of 1, cf. Table 1, form two-dimensional layers. A representative view of one selected two-dimensional layer is illustrated in Figure 2, showing the two-dimensional layers extending along the crystallographic b- and c-axes. Within the two-dimensional layers the formation of dimers of 1 with R²₂(8) type hydrogen bond interactions is also observed, as reported for 1×3H₂O (Oxtoby et al., 2005), cf. N2—H2N···O2ⁱⁱ in Table 1 and Figure 2. However, due to the N1—H1N···O1ⁱ, hydrogen bond cf. Table 1, the dimers are connected further to form the two-dimensional layers.

Additionally, individual molecules of 1 interact with each other by means of π interactions. They are approximately arranged in a parallel-displaced sandwich type configuration and thus form one-dimensional layers along the crystallographic a-axis, cf. Figure 3. Within such a one-dimensional chain, a head-to-tail arrangement is observed, as reported previously for 1×3H₂O (Oxtoby et al., 2005). Moreover, by analogy with 1×3H₂O, the π stacks of 1 are arranged orthogonal to the two-dimensional layers formed by intermolecular hydrogen bonds. The combinations of both supramolecular arrangements finally give rise to a three-dimensional network structure.

Experimental

Diethyl N,N'-naphthalene-bis(oxamate) was synthesized according to the literature (Rüffer et al., 2007). To a solution of diethyl naphthalene-bis(oxamate) (1.5 g, 9.49 mmol) in MeOH (50 ml) three equivalents of a solution of tert-BuNH₂ (2.05 g, 28.47 mmol) in MeOH (25 ml) were added. The solution was refluxed for 30 minutes, cooled to room temperature and concentrated to 30 ml. Diethyl ether (100 ml) was added and the resulting brown precipitate was filtered and dried on air. Yellow crystals of 1 were obtained by solvent diffusion of a dilute MeOH solution of 1 against Et₂O at room temperature. Yield: 0.7 g, 80%.