(E)-2-Cyano-N′-(1,2,3,4-tetrahydronaphthalen-1-ylidene)acetohydrazide

In the title compound, C13H13N3O, the tetrahydrobenzene ring adopts a half-boat (envelope) conformation. The mean plane of the tetrahydronaphthalene ring system forms a dihedral angle of 9.56 (6)° with the mean plane of the cyanoacetohydrazide group. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are connected by C—H⋯N hydrogen bonds into a chain propagating along [101]. The crystal packing also features C—H⋯π interactions.

In the title compound, C 13 H 13 N 3 O, the tetrahydrobenzene ring adopts a half-boat (envelope) conformation. The mean plane of the tetrahydronaphthalene ring system forms a dihedral angle of 9.56 (6) with the mean plane of the cyanoacetohydrazide group. In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds generate R 2 2 (8) loops. The dimers are connected by C-HÁ Á ÁN hydrogen bonds into a chain propagating along [101]. The crystal packing also features C-HÁ Á Á interactions.

sup-1
Acta Cryst. Tetralins (tetrahydronaphthalene derivatives) are of increasing interest since many of these compounds play a vital role in the biological activities because of their biological potentialities, for example, as potent agonists for D2-type receptors (Dutta et al., 2002), a treatment of Alzheimer's disease (Taddei et al., 2002) and as anti-cancer agents (Zaghary et al., 2005). Also, we found that certain substituted tetralin and heterocyclic derivatives show inhibition for cercarial serine protease (Bahgat & Khalifa, 2006), antioxidant (El Nezhawy et al., 2009) and antiinflammatory (Khalifa et al., 2008) activities. Tetralin derivative containing cyanoaceto-hydrazide was prepared as the title compound and its crystal structure is now reported.

Experimental
Equimolar amounts (0.01 mol) of tetralone and 2-cyanoacetohydrazide in dioxane (30 ml) were heated under reflux for 6 h. The mixture was then cooled at room temperature for overnight. The precipitated solid was filtered off, washed with ethanol, dried and crystallized from methanol to afford the title compound as colourless blocks with 73% abundance, m.p.: 183-185 °C.

Refinement
The atom H1N1 was located in a difference fourier map and refined freely [N1-H1N1 = 0.90 (2) Å]. The remaining H atoms were positioned geometrically [C-H = 0.93 and 0.97 Å] and refined using a riding model with U iso (H) = 1.2 U eq (C).

Figure 1
The molecular structure of the title compound with 30% probability displacement ellipsoids.

Special details
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.