Copper(II) complexes with 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone

Di-aqua-bis-{μ-1,5-bis-[(pyridin-2-yl)methyl-idene]carbonohydrazide(1-)}di-μ-chlorido-tetra-chlorido-tetra-zinc(II)

A tetra-nuclear Zn^II 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-yl-methyl-ene)carbono-hydrazide]. In the tetra-nuclear complex, each of the two ligand mol-ecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one Zn^II cation is penta-coordinated in a N₂OCl₂ in a distorted square-pyramidal geometry, while the other Zn^II cation is hexa-coordinated in a N₃OCl₂ environment with a distorted octa-hedral geometry. The basal plane around the penta-coordinated Zn^II cation is formed by one chloride anion, one oxygen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical position occupied by a chloride anion. The basal plane of the hexa-coordinated Zn^II cation is formed by one chloride anion, one hydrazinyl nitro-gen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetra-nuclear complex. A series of intra-molecular C-H⋯Cl hydrogen bonds is observed in each tetra-nuclear unit. In the crystal, the tetra-nuclear units are connected by inter-molecular C-H⋯Cl, C-H⋯O and N-H⋯O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.

Coordinating and supramolecular prospects of unsymmetrically substituted carbohydrazides

Unsymmetrically substituted carbohydrazides serve as multifunctional ligands, practicing their chelating and supramolecular roles with cis-dioxomolybdenum(vi) cationic core and the Lindqvist anion.

Discrete and polymeric ensembles based on dinuclear molybdenum(vi) building blocks with adaptive carbohydrazide ligands: from the design to catalytic epoxidation

Discrete and polymeric ensembles based on dimolybdenum(vi) units with adaptive carbohydrazide ligands are described. The polymeric complexes are efficient catalysts for cyclooctene epoxidation under eco-friendly conditions.