1-[(Z)-2-Phenylhydrazin-1-ylidene]-1-(piperidin-1-yl)propan-2-one

A Z configuration about the imine bond [1.3025 (18) Å] in the title compound, C14H19N3O, allows for the formation of an intramoleclar N—H⋯N hydrogen bond between the hydrazone H and piperidine N atoms; the carbonyl group is disposed to lie over the piperidine residue, which is in a chair form. A twist between the terminal benzene ring and the hydrazine residue is seen [N—N—C—C torsion angle = 163.81 (12)°]. Helical supramolecular chains along the c axis mediated by N—H⋯O hydrogen bonds are the most prominent feature of the crystal packing. The chains are connected into layers lying in the ac plane by weak C—H⋯π contacts involving two methylene H atoms and an adjacent benzene ring.

A Z configuration about the imine bond [1.3025 (18) Å ] in the title compound, C 14 H 19 N 3 O, allows for the formation of an intramoleclar N-HÁ Á ÁN hydrogen bond between the hydrazone H and piperidine N atoms; the carbonyl group is disposed to lie over the piperidine residue, which is in a chair form. A twist between the terminal benzene ring and the hydrazine residue is seen [N-N-C-C torsion angle = 163.81 (12) ]. Helical supramolecular chains along the c axis mediated by N-HÁ Á ÁO hydrogen bonds are the most prominent feature of the crystal packing. The chains are connected into layers lying in the ac plane by weak C-HÁ Á Á contacts involving two methylene H atoms and an adjacent benzene ring.

Comment
The title compound (I) and related amidrazone derivatives are known to possess biological activity (Frohberg et al., 2006), the motivation for on-going studies in this area (Abdel-Aziz & Mekawey, 2009;Abdel-Aziz et al., 2010). In the molecule of (I), Fig. 1, the configuration about the imine N2═C6 bond [1.3025 (18) Å] is Z. This places the hydrazone-N3-H in close proximity to the piperidinyl-N1 enabling the formation of an intramolecular N-H···N hydrogen bond ( Table 1). The carbonyl group is disposed to lie over the piperidinyl group which adopts a chair conformation. The benzene group is twisted out of the plane through the hydrazine residue to which it is connected as seen in the value of the N2-N3-C9-C10 torsion angle of 163.81 (12) °. The piperidinyl group is disposed to be almost normal to the rest of the molecule so that the dihedral plane formed through its least-squares plane and that through the O1,N2,N3,C6,C7,C9 atoms is 85.26 (6) °.
In the crystal, molecules are connected into a helical supramolecular chain mediated by N-H···O hydrogen bonds (Table 1). Chains are orientated along the c axis and are connected into a supramolecular array in the ac plane by C-H···π interactions involving methylene-H atoms associated with the bifurcated benzene ring (Table 1 and Fig. 2).

Experimental
This compound was prepared by the reaction of 2-oxo-N'-phenylpropanehydrazonoyl chloride with piperidine (Frohberg et al., 1995). The yellow prisms of (I) were isolated from its ethanol solution by slow evaporation at room temperature.

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H 0.95 to 0.99 Å, U iso (H) 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation. The amino-H atom was located in a difference Fourier map, and subsequently refined freely. Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.