N′-[(E)-3-Bromo-5-chloro-2-hydroxybenzylidene]furan-2-carbohydrazide

In the title compound, C12H8BrClN2O3, the furan ring makes a dihedral angle of 17.2 (2)° with the six-membered ring. An intramolecular O–H⋯N hydrogen bond stabilizes the molecular conformation. In the crystal, N–H⋯O hydrogen bonds connect the molecules into chains running along the c-axis direction. The crystal packing is additionally stabilized by C—H⋯O interactions into a three-dimensional supramolecular architecture.


Comment
Heterocyclic carbohydrazides are compounds with a wide spectrum of biological and analytical applications. They form stable metal chelates which find applications in molecular sensing (Bakir & Brown, 2002). A number of hydrazones derived from isoniazid were reported to be active antitubercular agents and were found to be less toxic than isoniazid (Rollas & Kucukguzel, 2007). Against this background, and in order to obtain detailed information on the molecular conformation in the solid state, an X-ray study of the title compound was carried out.
The X-ray analysis confirms the molecular structure and atom connectivity as illustrated in Fig. 1. The molecule exists in a E configuration with respect to the C6=N2 bond, with the C7-C6-N2-N1 torsion angle of 179.1 (2)°. The bond lengths and angles in the carbohydrazide group of the title compound can be compared with the related structures (Prabhu et al., 2011;Bikas et al., 2010). The furan ring makes a dihedral angle of 17.2 (2)° with the six-membered ring. The N2-N1-C5-O2 torsion angle of -0.1 (4)° indicates the cis configuration of the O2 atom with respect to the hydrazine nitro-  (Prasanna, et al., 2013) confirming that the carbohydrazide exists in solid state as an amido tautomer. An intramolecular O-H···N hydrogen bond stabilized the molecular conformation. Intermolecular N-H···O hydrogen bonds connect the molecules to chains running along the c axis. The crystal packing is further stabilized by C-H···O hydrogen bonds.

Refinement
The  The molecular structure of the title compound, showing the atomic numbering and displacement ellipsoids drawn at 30% probability level.

Figure 2
The crystal structure showing the R 2 2 (10) motif and also the formation of bifurcated R 1 2 (6) ring motif. For the sake of clarity, the H atoms not involved in the motif have been omitted.

N′-[(E)-3-Bromo-5-chloro-2-hydroxybenzylidene]furan-2-carbohydrazide
Crystal data An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.