TRIAZACYCLOHEXANES AS LIGANDS FOR TRIANGULAR TRIMETAL COMPLE XES

Triazacyclohexanes are ligands capable of binding three metals in a trinagular aray. A range of such complexes have been prepared and characterised containing three metals - either all equal, same metal but different oxidation states or two different metals. Thus, the system is suitable to model tri-metal enzymes.

A triangle of three metals occurs in several enzymes (often copper). The three metalls typically serve a multi-electron reservoirs. We found a suitable simple ligand capable of binding such a tri-metal cluster and we could show that different metals or oxidation states can be built in step-wise and thus selectively to probe the properties of such clusters in different stages of their reactivity as models of the enzymes.

Donor substituents have been found to generate air-stable tri-copper complexes which allow exchange of anionic ligands in aqueous media without loss of the metal coordination.
Step-wise synthesis of the clusters allow the selective formation and isolation of mixed oxidation-states and mixed metal clusters.