2-[(2Z,3E)-2-Hydroxyimino-5-phenyl-2,3-dihydro-3-thienylidene]-2-phenylacetonitrile

In the crystal structure of the title compound, C18H12N2OS, centrosymmetric dimers are stabilized both by van der Waals interactions and by two types of intermolecular O—H⋯N hydrogen bonds. In addition, an intramolecular C—H⋯S hydrogen bond is observed. The dihedral angles between the central ring and the two pendant phenyl rings are 7.4 (1) and 45.06 (9)°.

In the crystal structure of the title compound, C 18 H 12 N 2 OS, centrosymmetric dimers are stabilized both by van der Waals interactions and by two types of intermolecular O-HÁ Á ÁN hydrogen bonds. In addition, an intramolecular C-HÁ Á ÁS hydrogen bond is observed. The dihedral angles between the central ring and the two pendant phenyl rings are 7.4 (1) and 45.06 (9) .

D-HÁ
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IM2200).

Comment
Oximes can act both as donors and acceptors for hydrogen bonds, making them interesting materials for supramolecular chemistry (Bertolasi et al., 1982;Chertanova et al., 1994). Besides, oximes are among the most useful and versatile intermediates in synthetic organic chemistry, the Beckmann rearrangement and the reduction of oximes being two of the most useful transformations. Oximes are also interesting due to their wide application in medicine, industry and analytical chemistry. Owing to the oxime bond oxime derivatives also posses therapeuthic efficacy as a chemical tool for targeted intracellular delivery of synthetic oligonucleotides via conjugation to cell-penetrating peptides (Rappoport & Liebman, 2008). On the other hand, the discoveries of thiophene compounds in fungi and higher plants has awakened the interest of the natural product chemist in the chemistry of thiophenes (Gronowitz, 1963) Synthesis of thiophen-oximes resulted from our interest in the investigation of reactions between nitro-thiophene derivatives and arylacetonitriles. Due to containing oximic and nitrile moieties the title compound may be useful in prospective modifications. The molecule of the title compound is not planar: the phenyl moiety neighbouring to nitrile group is deviated from planarity by 45.06 (9)° and the second phenyl moiety is twisted by 7.4 (1)°. In the crystal structure solely the anti-isomer of the oxime is observed. The components of the structure are united into a three dimensional network by an extensive system of O-H···N intermolecular hydrogen bonds next to the intramolecular C(1)-H(1)···S(1) hydrogen bond. Adjacent molecules are linked into dimers by intermolecular O-H···N hydrogen bonds under participation of oximic groups. The distance between the nitrile nitrogen and oximic hydrogen atom of another molecule is 2.403 (2) Å. Dimers are further stacked in columns along the unique axis by π-π stacking interactions with centroid-centroid distances of 3.6 (1) Å.

Experimental
To 40 ml of a methanolic solution of potassium hydroxide (3.36 g, 60 mmoles) phenylacetonitrile (1.17 ml, 10 mmol) was added with stirring. Then 10 ml of a methanolic solution of 2-iodo-5-nitrothiophene (2.55 g, 10 mmol) was added to the reaction mixture. The suspension was stirred at room temperature until precipitation of product was ended. The reaction mixture was then poured into 100 ml of water and acidified by adding acetic acid. The precipitate was isolated by filtration, washed with water and dried. Red (orange) needles of title compound, m.p. (with decomp.) 394-395 K, yield 2.12 g (60%), were obtained after slowly cooling down an ethanolic solution.

Refinement
Positions of H atoms were calculated and refined using SHELXL constraints. All H atoms, including one bonded to O, were positioned geometrically with O-H = 0.82 Å and with C-H = 0.93 Å. Finally, thermal parameters of all hydrogen atoms were refined using an overall thermal isotropic parameter excluding the hydrogen atom of OH-group. Thermal parameter for hydrogen of OH-group was refined individually.  Fig. 1. Molecular structure of the title compound, C 18 H 12 N 2 OS. Thermal ellipsoids represent a 50% probability level.  as those based on F, and R-factors based on ALL data will be even larger.