5-Bromo-2-methoxy-4-{[(4-methoxyphenyl)imino]methyl}phenol monohydrate

The crystal structure of the title compound, C15H14BrNO3·H2O, has a trans configuration about the central C=N double bond. An intramolecular O—H⋯O hydrogen bond occurs in the main molecule. The crystal packing is stabilized by strong O—H⋯O and O—H⋯N hydrogen bonds.


Comment
The 2-bromo-4-hydroxy-5-methoxybenzaldehyde can react with organic amines to form a range of Schiff bases. Schiff base compounds are well known for their wide range of biological activities and have contributed to the development of coordination chemistry related to catalysis, enzymatic reactions, magnetism and molecular architecture (Zhu et al., 2005). Here, We report one of the schiff bases which is structrually characterized to promote the development of coordination chemistry. The title compound displays a trans-configuration with respect to the C(7)=N(1) double bond. The compound crystallized in the orthorhombic system with one title compound molecule and a water molecule in the asymmetric unit. There is a π-π interaction (symmetry code: 3/2-X,1/2+Y,Z) [centroid-centroid distance =3.758 (3) Å ] There are also O(4)-H(1W)···O (1) and O(4)-H(2W)···N(1) hydrogen bonds with symmetry codes (1-x,1/2+y,1/2-z)and (-1/2+x,y,1/2-z) respectively ( Figure   2 and table 1).

Experimental
The 2-bromo-4-hydroxy-5-methoxybenzaldehyde (0.1155 g) and 4-methoxyaniline (0.0616 g) were dissolved in methanol (20 mL) and reacted at room temperature for 30 mins to give a clear solution. The solution after standingin in air for 5 days gave yellow block-shaped single crystals at the bottom of the reaction vessel which were suitable for X-ray diffraction analysis.

Refinement
All H atoms were placed in geometrical positions and constrained to ride on their parent atoms with C-H distances in the range 0.93-0.96 Å, They were treated as riding atoms, with U iso (H) = kU eq (C), where k = 1.5 for methyl and 1.2 for all other H atoms. Fig. 1. The structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

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 > 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.