Crystal structure of 2-{[(5-nitrothiophen-2-yl)methylidene]amino}phenol

The title compound, C11H8N2O3S, is roughly planar; the dihedral angle between the planes of the thiophene and benzene rings is 8.38 (10)°. An intramolecular O—H⋯N hydrogen bond generates an S(5) ring motif. In the crystal, molecules are linked into centrosymmetric dimers by pairs of O—H⋯O hydrogen bonds with an R 2 2(22) graph-set motif. Aromatic π–π stacking interactions [centroid–centroid separations = 3.653 (3) and 3.852 (3) Å] link the dimers into a three-dimensional network.


S1. Comment
Schiff bases have long been employed as ligands for the complexation of metal ions (Aydoğan et al., 2001;Tanak et al., 2009).
In the title compound ( Fig. 1), the molecular structure is almost planar. The dihedral angle between the C1-C4/S1 thiophene and the C6-C11 phenyl rings is 8.38 (10)°. The imino group is coplanar with the nitrothiophene ring as it can be shown by the C3-C4-C5-N2 torsion angle is 178.60 (19)°. The length of the C5=N2 double bond is 1.264 (2) Å, it is slightly shorter than standart 1.28 Å value of C=N double bond and consistent with the related stuructures (Tanak et al., 2013;Tanak et al., 2014). The C1-S1 and C4-S1 bond lengths of the thiophene ring are slightly different than the accepted value for an Csp 2 -S single bond (1.76 Å), resulting from the conjugation of the electrons of atom S1 with atoms C1 and C4 (Tanak et al., 2014).
A packing diagram of the title compound is shown in Fig. 3.
The reaction mixture was stirred for 5 h under reflux. Single crystals of the title compound for X-ray analysis were obtained by slow evaporation of an ethanol solution (yield 60%; m.p. 430-432 K).

S3. Refinement
C-bound H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C). The position of the H1 atom was obtained from a difference map of the electron density in the unit-cell and was refined freely.

Figure 1
The molecular structure of the title compound, showing 30% probability diplacement ellipsoids.

Figure 3
Packing diagram of the title compound. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.89 e Å −3 Δρ min = −0.45 e Å −3 Special details Experimental. 360 frames, detector distance = 80 mm Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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 > σ(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.