2-(2-Fluorobiphenyl-4-yl)-N′-(propan-2-ylidene)propanohydrazide

In the title compound, C18H19FN2O, the hydrazide side chain is approximately perpendicular to the central ring [dihedral angle = 76.80 (5)°]. The F atom is disordered over two positions with occupancies of 0.818 (2) and 0.182 (2). The packing consists of chains of molecules parallel to the a axis, connected by a bifurcated N—H⋯(O,N) hydrogen bond and a weak Cphenyl—H⋯O hydrogen bond. The packing is extended to a layer structure parallel to the ab plane by a weak Cphenyl—H⋯F hydrogen bond.

In the title compound, C 18 H 19 FN 2 O, the hydrazide side chain is approximately perpendicular to the central ring [dihedral angle = 76.80 (5) ]. The F atom is disordered over two positions with occupancies of 0.818 (2) and 0.182 (2). The packing consists of chains of molecules parallel to the a axis, connected by a bifurcated N-HÁ Á Á(O,N) hydrogen bond and a weak C phenyl -HÁ Á ÁO hydrogen bond. The packing is extended to a layer structure parallel to the ab plane by a weak C phenyl -HÁ Á ÁF hydrogen bond.   Table 1 Hydrogen-bond geometry (Å , ). (3) 3.0633 (17) 158 (2) (Küçükgüzel et al. 2007;Navidpour et al., 2006;Stocks et al., 2004). The title compound (I) was synthesized as an intermediate for onward conversion to 1,2,4-triazoles and 1,3,4-thiadiazoles and in order to explore their anti-bacterial, urease inhibition and anti-fungal activities.

D-HÁ
The molecule of (I) is shown in Fig. 1. Molecular dimensions such as the bond lengths C16═N1 1.280 (2)

Experimental
Methyl 4-ethoxybenzoate (0.02 moles) was dissolved in 40 ml methanol in a round-bottom flask fitted with a reflux condenser and a calcium chloride drying tube. Hydrazine hydrate (80%, 0.04 moles) was added slowly and the progress of the reaction was monitored by thin layer chromatography. After completion of the reaction, the contents were concentrated under reduced pressure (Furniss et al., 1989). The resulting crude solid was filtered, washed with water and agitated with freshly distilled acetone for 1 h. The product was recrystallized from aqueous ethanol.

Refinement
The NH hydrogen was refined freely. Methyl hydrogens were identified in difference syntheses, idealised and refined as rigid groups with C-H 0.98 Å and H-C-H angles 109.5°, allowed to rotate but not tip. Other hydrogens were placed in calculated positions and refined using a riding model with C-H arom 0.95 and C-H methine 1.00 Å; the hydrogen U values were fixed at 1.5 (methyl) or 1.2 × U(eq) of the parent atom.
The fluorine atom is disordered over the two sites at C3 and C5 with occupancies 0.818 (2),0.182 (2). The methyl hydrogens at C18 are treated as an idealised hexagon (disordered over two equally occupied sites) and the short contact to O may not be structurally significant.
supplementary materials sup-2 In the absence of significant anomalous dispersion, the Friedel opposites were merged and the Flack parameter is thus meaningless. Fig. 1. The molecule of the title compound. Ellipsoids correspond to 50% probability levels. The minor disorder component is omitted. Fig. 2. Packing diagram of the title compound viewed parallel to the z axis in the region z ≈ 0. Classical (three-centre) H bonds are indicated by thick dashed lines and "weak" H bonds by thin dashed lines. For clarity, the ring C7-12 is represented only by the ipso C atom .

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.