5-Nitro-2,3-bis(thiophen-2-yl)quinoxaline

The structure of a nitro-bis(thiophen-2-yl)quinoxaline has been determined at 298 K.


Structure description
5-Nitro-2,3-bis(thiophen-2-yl)quinoxaline crystallizes in space group P2 1 . All bond lengths and angles are within expected values. The nitro group makes a angle of 43.07 (6) with respect to the mean plane of the quinoxaline unit. This angle is comparable to the angles of 44.96 and 50.93 observed for the two molecules in the asymmetric unit in the published crystal structure of 5-nitro-2,3-bis(2-pyridyl)quinoxaline (Du & Zhao, 2003) and with the 44.12 determined in a corresponding silver complex with the pyridyl ligand (Liu & Du, 2002). The thienyl rings make angles of 35.16 (5) and 24.94 (3) , for rings with S1 and S2 respectively, with the mean plane of the quinoxaline unit. Both the heterocyclic thienyl ring sulfur atoms reside in close proximity to the quinoxaline N atoms. When describing the structure of 5-nitro-2,3-bis(2-pyridyl)quinoxaline, Du & Zhao (2003) labeled this orientation of the heterocyclic ring to the quinoxaline unit as a trans-trans arrangement. There are no intermolecular interactions of consequence. An ORTEP view is shown in Fig. 1 and a view of the unit cell along (010) is shown in Fig. 2.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1.

Funding information
This research was funded by a CCSU-AAUP research grant.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

data-2
IUCrData (2020). 5, x200196 Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. H atoms were included in calculated positions with C-H distances of 0.93 Å and were included in the refinement in riding motion approximation with U iso = 1.2 of the carrier atom.