(E)-4-Octyloxybenzaldehyde thiosemicarbazone

In the title compound, C16H25N3OS, the thiosemicarbazone group adopts an E configuration with respect to the C=N bond and is almost coplanar with the benzene ring, forming a dihedral angle of 9.3 (1)°. In the crystal packing, the molecules lie along the a axis in an antiparallel arrangement and are held in place by van der Waals interactions. As a consequence, there is relatively low anisotropic thermal motion in the terminal atoms of the n-octyl chain.

In the title compound, C 16 H 25 N 3 OS, the thiosemicarbazone group adopts an E configuration with respect to the C N bond and is almost coplanar with the benzene ring, forming a dihedral angle of 9.3 (1) . In the crystal packing, the molecules lie along the a axis in an antiparallel arrangement and are held in place by van der Waals interactions. As a consequence, there is relatively low anisotropic thermal motion in the terminal atoms of the n-octyl chain.

Comment
When used in coordination chemistry this molecule is potentially a bidentate ligand acting through the α-or β-nitrogen and thiolate sulfur anion forming a four-and five-membered chelate ring, respectively (Pal et al., 2002), although a behavior as monocoordinated ligand through sulfur has also been reported (Tian et al., 2002). In the crystal structure the molecules are interconnected by N-H···N and N-H···S hydrogen bonds as found in other thiosemicarbazone species (Narayana et al., 2007;Tarafder et al., 2008). The crystal structure is also stabilized by C-H···π interactions. The octyl chain presents an anti conformation with the exception of the O1-C9-C10-C11 part that has a torsion angle of -72.7 (3)°.
Experimental 4-n-octyloxybenzaldehyde (6.09 g, 26 mmol) was added to a hot solution of thiosemicarbazide (2.38 g, 26 mmol) in methanol (200 ml). The mixture was refluxed for 30 min and cooled down to room temperature. The product was recrystallized from dichloromethane to give colorless microcrystals. M.P. 381 K. Brilliant colorless flat rectangular shaped crystals suitable for X-ray difraction were obtained from a mixture of dichloromethane and toluene (10:5; v/v) after 5 days.

Refinement
Data collection was performed on a image plate with a phi scan over 180° that allows to get a completion (for the triclinic space group) of 97%. All H atoms were located geometrically and treated as riding atoms, with C-H = 0.93-0.96 Å, N-H = 0.86 and with Uĩso~(H) = 1.2U~eq~(C or N) or 1.5U~eq~(C) for methyl H atoms. Fig. 1. ORTEP drawing (ellipsoids at the 40% probability level) of the compoud with atomlabelling scheme.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The 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 > 2σ(F 2 ) is used only for calculating Rfactors(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.