Solvent induced reactivity of 3,5-dimethylpyrazole towards zinc (II) carboxylates

Abstract

The reactions of 3,5-dimethylpyrazole with zinc(II)acetate dihydrate and varieties of aromatic carboxylic acids led to formation of mono-nuclear zinc complexes of composition [Zn(HDMP)₂(RCO₂)₂] (R = C₆H₅, p-CH₃-C₆H₄, p-NO₂-C₆H₄etc.HDMP = 3,5-dimethylpyrazole) in methanol, whereas the same reactants in dimethylformamide (DMF) gave binuclear 3,5-dimethylpyrazolato bridged zinc carboxylate complexes containing monodentate 3,5-dimethylpyraozole ligands with composition [Zn₂(μ-DMP)₂(HDMP)₂(RCO₂)₂]. The mononuclear complexes can be converted to the corresponding binuclear complexes by simply dissolving in DMF. The reaction of zinc(II)acetate dihydrate with p-nitrobenzoic acid and 3,5-dimethylpyrazole in different solvents gave solvated mononuclear complexes of the corresponding solvent. All these solvated complexes having the core [Zn(HDMP)₂(p-NO₂-C₆H₄CO₂)₂] contain two structurally independent molecules in the asymmetric unit (Z′ = 2).