(E)-1-Phenylethanone semicarbazone

In the title compound, C9H11N3O, the benzene ring is disordered over two positions with refined occupancies of 0.922 (5) and 0.078 (5). The program PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155] recommends the solution in the space group C2/m with a = 7.3050 (3), b = 6.6745 (2), c = 18.3853 (6) Å and β = 96.986 (2)°. However, the large number of non-extinct reflections needed to be ignored if C2/m is chosen suggested that the space group is incorrect, even though the R values are lower than that for P21/c. The semicarbazone group is essentially planar, with a maximum deviation of 0.046 (1) Å for one of the N atoms. The mean plane of the semicarbazone group forms dihedral angles of 33.61 (8) and 39.1 (9)° with the benzene ring of the major and minor components, respectively. In the crystal structure, molecules are linked by intermolecular N—H⋯O hydrogen bonds into extended chains along the c axis. The crystal structure is further stabilized by weak intermolucular C—H⋯π interactions.

In the title compound, C 9 H 11 N 3 O, the benzene ring is disordered over two positions with refined occupancies of 0.922 (5) and 0.078 (5). The program PLATON [Spek (2009). Acta Cryst. D65, [148][149][150][151][152][153][154][155] recommends the solution in the space group C2/m with a = 7.3050 (3), b = 6.6745 (2), c = 18.3853 (6) Å and = 96.986 (2) . However, the large number of non-extinct reflections needed to be ignored if C2/m is chosen suggested that the space group is incorrect, even though the R values are lower than that for P2 1 /c. The semicarbazone group is essentially planar, with a maximum deviation of 0.046 (1) Å for one of the N atoms. The mean plane of the semicarbazone group forms dihedral angles of 33.61 (8) and 39.1 (9) with the benzene ring of the major and minor components, respectively. In the crystal structure, molecules are linked by intermolecular N-HÁ Á ÁO hydrogen bonds into extended chains along the c axis. The crystal structure is further stabilized by weak intermolucular C-HÁ Á Á interactions.

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. Semicarbazone find immense applications in the field of synthetic chemistry, such as medicinal chemistry (Warren et al., 1977), organometalics (Chandra & Gupta, 2005), polymers (Jain et al., 2002) and herbicides (Pilgram, 1978). 4-Sulphamoylphenyl semicarbazones were synthesized and were found to possess anticonvulsant activity (Yogeeswari et al., 2004). We hereby report the crystal structure of a semicarbazone of potential commercial importance, (I).

Experimental
Semicarbazide hydrochloride (1.0 g, 8.9 mmol) and freshly recrystallized sodium acetate (0.9 g, 10.9 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, (1.0 g, 8.32 mmol) acetophenone was added and shaken well. A little alcohol was added to dissolve the turbidity. It was shaken for 10 more minutes and allowed to stand. The semicarbazone crystallizes on standing for 6 h. The separated crystals were filtered, washed with cold water and recrystallized from alcohol. Yield: 1.37 g (93%). M.p.

Refinement
All hydrogen atoms were located in a difference Fourier map and refined freely. The benzene ring is disordered over 2 position with refined occupancies of 0.922 (5) and 0.078 (5). The program PLATON recommends the solution in C2/m space group with a = 7.3050 (3), b = 6.6745 (2), c = 18.3853 (6) Å and β = 96.986 (2)°. However the large number of non-extinct (i.e. observed) reflections needed to be ignored for the C2/m case suggested that the space group is incorrect even though the R-values are lower than that for P2 1 /c. Fig. 1. The molecular structure of the title compound with atom labels and 50% probability ellipsoids for non-H atoms. All disorder components are shown. The minor disorder component is shown with open bonds.   Glazer, 1986) operating at 100.0 (1)K.

sup-2 Figures
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.