5-Diethylamino-2-{[2-(2,4-dinitrophenyl)hydrazin-1-ylidene]methyl}phenol

In the title compound, C17H19N5O5, obtained from the condensation reaction of 4-diethylamino-2-hydroxybenzaldehyde and 2,4-dinitrophenylhydrazine, the two benzene rings are twisted by a dihedral angle of 1.75 (12)°. The nitro groups are slightly twisted with the respect to the benzene ring to which they are attached, making dihedral angles of 8.20 (15) and 5.78 (15)°. An intramolecular O—H⋯N hydrogen bond occurs. In the crystal, molecules are linked by pairs of intermolecular N—H⋯O hydrogen bonds, forming dimers through R 2 2(12) rings. These dimers are further linked by C—H⋯O and C—H⋯π and weak slipped π–π interactions [centroid–centroid distance = 3.743 (2)Å]. One of the ethyl groups is disordered over two positions, with occupancy factors in the ratio 0.72:0.28.

In the title compound, C 17 H 19 N 5 O 5 , obtained from the condensation reaction of 4-diethylamino-2-hydroxybenzaldehyde and 2,4-dinitrophenylhydrazine, the two benzene rings are twisted by a dihedral angle of 1.75 (12) . The nitro groups are slightly twisted with the respect to the benzene ring to which they are attached, making dihedral angles of 8.20 (15) and 5.78 (15) . An intramolecular O-HÁ Á ÁN hydrogen bond occurs. In the crystal, molecules are linked by pairs of intermolecular N-HÁ Á ÁO hydrogen bonds, forming dimers through R 2 2 (12) rings. These dimers are further linked by C-HÁ Á ÁO and C-HÁ Á Á and weak slippedinteractions [centroid-centroid distance = 3.743 (2)Å ]. One of the ethyl groups is disordered over two positions, with occupancy factors in the ratio 0.72:0.28.   Table 1 Hydrogen-bond geometry (Å , ).

Experimental
Cg2 is the centroid of the C8-C13 ring. Structural information for phenylhydrazone derivatives is useful in studying their coordination properties. As part of our work, we have synthesized the title compound and report the crystal structure.
The C15 atom is distributed over two positions C15 and C15B. The occupancy factor with the sum of the occupancy factor constraints to be 1.0, was first refined using a overall isotropic thermal parameter for the two carbon atoms. Once the occupancy factor has been determined, it was fixed and the isotropic thermal parameters were freely refined. The geometry of the ethyl has been kept chemically reasonable using restraints (SAME, Sheldrick, 2008). Using such disoredered model improved greatly the refinement.

Special details
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 > σ(F 2 ) is used only for calculating Rfactors(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.

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