Oxalato as polyatomic coordination center and magnetic coupler in copper(II)-polypyrazole inverse polynuclear complexes and coordination polymers

The present review provides an overview on inverse coordination chemistry and magnetochemistry of copper(II) systems with oxalato as polyatomic coordination center and polypyrazoles with amino, methyl, iso-propyl, carboxymethyl, phenyl, benzyl, or pyrimidine substituents as terminal ligands. Special attention is paid to the syntheses, structural, reactivity, and magnetic properties of oxalato- centered copper(II)-polypyrazole inverse polynuclear complexes (IPCs) and multidimensional inverse coordination polymers (ICPs). New magneto-structural correlations emerge from the study of these low-dimensional IPCs and ICPs, ranging from di- to hexanuclear species up to chain-like systems with either ferro- or antiferromagnetic interactions, which have eventually led to high-dimensional sheet- like systems with chemoswitching magnetic behavior for biogenic amine sensing. Future trends in this area will be focused on the design and synthesis of a new class of mixed oxalato-centered ICPs with poly- triazoles as additional bridging ligands featuring porous 3D net structures, referred to as inverse metal– organic frameworks (IMOFs), as prototypes of magnetic sensors for the chemical sensing of volatile organic compounds (VOCs) of biological, environmental or industrial interest.