(E)-1-(4-Fluorophenyl)ethan-1-one semicarbazone

In the title compound, C9H10FN3O, the semicarbazone group is nearly planar, with the maximum deviation of 0.044 (1) Å for one of the N atoms. The mean plane of semicarbazone group forms a dihedral angle of 30.94 (4)° with the benzene ring. The molecules are linked into a supramolecular chain by N—H⋯O hydrogen bonds formed along the c axis. The crystal structure is further stabilized by weak intermolucular C—H⋯π interactions; the closest C⋯Cg contact is 3.6505 (11) Å.

In the title compound, C 9 H 10 FN 3 O, the semicarbazone group is nearly planar, with the maximum deviation of 0.044 (1) Å for one of the N atoms. The mean plane of semicarbazone group forms a dihedral angle of 30.94 (4) with the benzene ring. The molecules are linked into a supramolecular chain by N-HÁ Á ÁO hydrogen bonds formed along the c axis. The crystal structure is further stabilized by weak intermolucular C-HÁ Á Á interactions; the closest CÁ Á ÁCg contact is 3.6505 (11) Å .

Comment
In organic chemistry, a semicarbazone is a derivative of an aldehyde or ketone formed by a condensation between a ketone or aldehyde and semicarbazide. Semicarbazones find a large number of applications in the field of synthetic chemistry, such as in medicinal chemistry (Warren et al., 1977), organometallics (Chandra & Gupta, 2005), polymers (Jain et al., 2002), and herbicides (Pilgram, 1978). 4-Sulphamoylphenyl semicarbazones were found to possess anti-convulsant activity (Yogeeswari et al., 2004). We hereby report the crystal structure of a semicarbazone of commercial importance, (I).
The bond lengths and angles for (I), Fig. 1, are comparable to those found in related structures (Fun et al., 2009a, b). A maximum deviation of 0.044 (1) Å for atom N2 from the mean plane formed by atoms O1, N1, N2, N3, C6, C7, C8 and C9, indicates that the semicarbazone group is nearly planar. This mean plane makes a dihedral angle of 30.94 (4)° with the C1-C6 benzene ring. The molecules are linked into one-dimensional chains by intermolecular N-H···O hydrogen bonds along the c axis (Fig. 2); these hydrogen bonding interactions generate R 2 2 (8) ring motifs (Bernstein et al., 1995). The crystal structure is stabilized by weak intermolecular C-H···π interactions (Table 1).

Experimental
Semicarbazide hydrochloride (0.86 g, 7.70 mmol) and freshly recrystallized sodium acetate (0.77 g, 9.40 mmol) were dissolved in water (10 ml) following a literature procedure (Furniss et al., 1978). The reaction mixture was stirred at room temperature for 10 minutes. To this, 4-fluoroacetophenone (1.00 g, 7.23 mmol) was added and the mixture was shaken well.
A little alcohol was added to dissolve the turbidity. The mixture was shaken for a further 10 minutes and allowed to stand.
The title compound (I) crystallizes on standing for 6 h. The separated crystals were filtered, washed with cold water and recrystallized from ethanol. Yield: 1.34 g (95%). M.p. 485-486 K.

Refinement
All hydrogen atoms were located from the difference Fourier map and refined freely, N-H = 0.820 (19) Fig. 1. The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.
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.
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 > 2sigma(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.