3-Amino-N′-(2-oxoindolin-3-ylidene)benzohydrazide

The title compound, C15H12N4O2, contains two substituted benzohydrazide and indole rings linked via a C=N double bond. The dihedral angle between the benzene ring and the indole ring system is 11.38 (10)°. The molecular structure is stabilized by an intramolecular N—H⋯O hydrogen bond, forming a six-membered ring. The crystal structure is consolidated by intermolecular N—H⋯O and C—H⋯O interactions, which result in sheets.

The title compound, C 15 H 12 N 4 O 2 , contains two substituted benzohydrazide and indole rings linked via a C N double bond. The dihedral angle between the benzene ring and the indole ring system is 11.38 (10) . The molecular structure is stabilized by an intramolecular N-HÁ Á ÁO hydrogen bond, forming a six-membered ring. The crystal structure is consolidated by intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO interactions, which result in sheets.

Comment
Compounds containing hydrazide moiety have been revealed to exhibit a wide variety of interesting biological properties (Ashiq et al. 2008;Maqsood et al. 2006). In a quest to expand and further explore the biological significance of hydrazides, we have undertken a task to synthesize new Schiff bases of isatin with hydrazides. Isatins are very important compounds due to their antifungal properties (Sarangapani & Reddy, 1994). In this article we report the synthesis and crystal structure of the title compound.
The title molecule ( Fig. 1) consists of substituted benzohydrazide and indole rings linked by C═N bond. The dihedral angle between the two substituted benzene (C10-C15) and indole ring (N1/C1-C8) is 11.38 (10)°. The bond lengths and angles are in normal range as in other structurally related compounds (Bai et al. 2006;Yang & Pan, 2004). The geometry of the molecule is stabilized by N3-H3A···O1 intramolecular hydrogen bond resulting in a six membered ring.

Experimental
To a solution of 2,3-indolinedione (10 mmol, 1.47 g) in 15 ml of ethanol with a few drops of glacial acetic acid and 3aminobenzohydrazide (10 mmol, 1.51 g) in 15 ml ethanol were added. The mixture was refluxed for 2 h and a solid was obtained upon removal of the solvent by rotary evaporation. The resulting solid was washed with ethanol to afford the title compound (yield 75%). The crystals of the title compound suitable for XRD analysis were grown from a mixture of ethanol and methanol (1:1) by slow evaporation at room temperature.

Refinement
H atoms on the C atoms and N1 and N3 were positioned geomatrically with C-H = 0.93 and N-H = 0.86 Å and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C/N). The H atoms on N4 were located from a difference Fourier map and refined isotropically.