4-Phenyl-1H-1,5-benzodiazepin-2(3H)-one

In the title compound, C15H12N2O, the phenyl ring makes a dihedral angle of 32.45 (9)° with the benzene ring of the 1,5-benzodiazepin-2-one unit. The seven-membered ring adopts a boat conformation with the methylene group as the prow and the fused benzene-ring C atoms as the stern. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are further linked by C—H⋯O hydrogen bonds, so forming a column along the a-axis direction.

In the title compound, C 15 H 12 N 2 O, the phenyl ring makes a dihedral angle of 32.45 (9) with the benzene ring of the 1,5benzodiazepin-2-one unit. The seven-membered ring adopts a boat conformation with the methylene group as the prow and the fused benzene-ring C atoms as the stern. In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds generate R 2 2 (8) loops. The dimers are further linked by C-HÁ Á ÁO hydrogen bonds, so forming a column along the a-axis direction.
Manchester Metropolitan University, Erciyes University and University of Strathclyde are gratefully acknowledged for supporting this study.
have attracted the interest of chemists and biologists. They are widely used as anti-inflammatory, analgesic, hypnotic, tranquillizers and anti-depressive agents (e.g. Thakur et al. 2003;McKernan, 2000).
In the title molecule (I), (Fig. 1), the C10-C15 phenyl and C3-C8 benzene rings make a dihedral angle of 32.45 (9)° with each other. All bond lengths and bond angles in (I) are comparable to those reported for similar compounds (Višnjevac et al., 2002;Benelbaghdadi et al., 2003).
In the crystal, a pair of N-H···O hydrogen bonds (Table 1) link two molecules into an inversion dimer with an R 2 2 (8) motif. Furhermore, C-H···O hydrogen bonds link the dimers, so forming a column along the a axis direction (Fig. 2).

Experimental
To a stirred boiling solution of 0.1 mol (10.8 g) benzene-1,2-diamine in 100 ml p-xylene, 0.12 mol (23.12 g) ethyl 3oxo-3-phenylpropanoate was added in dropwise and refluxed for 2 h. The reaction mixture was left to stand at room temperature for 24 h. The precipitated solid was collected by filtration and recrystallized from benzene to give colourless rods in 90% yield (M.p. 480 K).

Refinement
The amine H atom was located from a difference map and refined with a distance restraint of N-H = 0.91 (2) Å. H atoms bound to C atoms were positioned geometrically and refined using a riding model [C-H = 0.95-0.99 Å, and

Computing details
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009  The molecular structure of (I) with displacement ellipsoids for non-H atoms drawn at the 50% probability level. Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.5985 (