Crystal structure of bis(pyridine-2-carboxaldehyde-2-hydroxybenzoyl hydrazone)zinc(II) semihydrate, Zn(C13H10N3O2)2 · 0.5 H2O

Abstract

Source of materialThe ligand pyridine-2-carboxaldehyde-2-hydroxybenzoylhydrazone (pabh) was prepared according to the literature procedure [1]. To the solution of pabh (0.048 g, 0.2 mmol) dissolved in 10 ml methanol was added dropwise 15 ml solution of methanol containing Zn(OOCCH 3)2 · 2H2O (0.022 g, 0.1mmol) with stirring and continuously stirred for 30 min. A solution of concentrated HCl and methanol (1:50, v/v) was added dropwise to the above mentioned solution with stirring until no precipitates were appeared. The reaction mixture was neutralized with 1mol/l NaOH to clear aqueous and filtered. With the filtrate slowly evaporating in ambient temperature for 30 days, yellow crystals were appeared. DiscussionThe ligand pyridine-2-carboxaldehyde-2-hydroxybenzoylhydrazone is usually coordinated to metal ions as tridentate chelate. When the neutral ligand molecule deprotonated it plays the role of the counterion. If it is coordinated to metal ions as an neutral ligand, some counterions are needed to balance the charge of its coordination compound [2,3]. The symmetrically independent unit consists of two deprotonated pabh moleculues, half water molecule and one Zn(II) ion with ZnN 4O2 coordination. Different bond lengths between Zn andgive evidence of distortion of the ideal octahedral symmetry. More significant distortion can be seen from the large range of bond angles around Zn metal center from 74.1°to 149.9°. Two nitrogen atoms (N3, N6) of two distinct pyridyl rings are located in the apical, two oxygen atoms (O1, O2) and two nitrogen atoms (N2, N5) are in the equatorial positions.