Diaquabis{μ-1,5-bis[(pyridin-2-yl)methylidene]carbonohydrazide(1–)}di-μ-chlorido-tetrachloridotetrazinc(II)

Abstract

A tetranuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](μCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2 L [1,5-bis(pyridin-2-ylmethylene)carbonohydrazide]. In the tetranuclear complex, each of the two ligand molecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is pentacoordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexacoordinated in a N3OCl2 environment with a distorted octahedral geometry. The basal plane around the pentacoordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical position occupied by a chloride anion. The basal plane of the hexacoordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitrogen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetranuclear complex. A series of intramolecular C—H...Cl hydrogen bonds is observed in each tetranuclear unit. In the crystal, the tetranuclear units are connected by intermolecular C—H...Cl, C—H...O and N—H...O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.

Synthesis of Mono and Bis-Substituted Compounds 1-(2-hydroxybenzylidene) Carbonohydrazide and 1, 5-bis(2-Hydroxybenzaldehyde) Carbohydrazone: Study Spectroscopy and X-ray Diffraction

“…"It has been reported in the literature that dicarbonohydrazone with their cis-enol conformations or cis-enol and trans association lead to square or rectangular grid polynuclear complexes, respectively, with interesting physical properties" [23]. In these coordination compounds, the dicarbonohydrazone act as  2 -O [24,25,26] and/or  2 -N-N bridged pentadentate or hexadentate ligand [37][38][39][40]. Depending on their tridentate or tetradentate behavior, monocarbonohydrazide yield, generally, mononuclear or dinuclear complexes with transition metal ions [21].…”