3,5-disusbtituted-N-hydroxyalkylpyrazole Cu(II) compounds: Anion effect on dimensionality, supramolecular structure and magnetic properties

Abstract

The coordination behaviour of N,O-hybrid pyrazole ligand 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethanol (HL) against different Cu(II) salts has been studied. Five coordination complexes (1-5) have been synthesized and characterized by elemental analysis, conductivity measurements and spectroscopic measurements. Moreover, the crystal structure of all five compounds has been elucidated, allowing the detailed study of their molecular and supramolecular structure. The obtained compounds are structurally diverse, as ionic monomers, neutral dimers and a polymer have been isolated. Their nuclearity seems to be very dependent on the deprotonation of the pyrazole moiety, whereas co-ligands have a direct influence on their dimensionality and supramolecular structure. Upon crystallization, compound 5 adsorbs water molecules, resulting in a particularly intriguing supramolecular network. In this scaffold, the presence of three water moieties playing different supramolecular roles has been analysed via computational methods and thermogravimetric analyses. Lastly, magnetic susceptibility measurements have been carried out for 3 and 5 and the results were rationalized on account of their structure.