A number of dicopper(II) complexes containing binucleating, primarily nitrogen donor ligands havingm-xylyl spacers between the coordination units of relevance to tyrosinase activity and a brief account of the recent results obtained using a new non-Schiff base binucleating ligand providing only two-nitrogen coordination at each copper centre are described in this paper. This new system exhibits tyrosinase activity. A dihydroxo-bridged copper(II) complex has also been obtained with a novel ligand assembly formed as an impurity during our desired ligand synthesis. A brief review has been presented in this field emphasising the nature of the ligand systems and the reaction conditions.

Activation of dioxygen on dicopper(I) centres was systematically investigated using a group of open-chain and a macrocyclicm-xylyl-based dinucleating ligand from a bioinorganic viewpoint. Even though intermediate peroxodicopper(II) species was not detected (even at −80°C for the open-chain system), the putative intermediate reacted with C–H groups in ligands giving oxygenated products (C–OH groups). Absorption, spectroscopic and magnetic properties of the final dicopper(II) complexes have been investigated.