Chalcogen Bonding in the Decoration of the Secondary Coordination Sphere of Copper(II) Complexes: Activation of Nitriles, the Auxiliary Ligand Substituent Effect

The design of the secondary coordination sphere of metal complexes has emerged as a powerful synthetic strategy in their application/function in catalysis, molecular recognition, and crystal engineering. In contrast to traditional approaches, herein, the secondary coordination sphere of copper(II) complexes was designed by using chalcogen (sulfur) bond donor auxiliary ligands (5-substituted-1,3,4-thiadiazol-2-amines) in one-pot activation of one nitrile group in an arylhydrazone ligand. The chalcogen bond donor ability of the auxiliary ligands markedly increases with the electron-withdrawing character of the substituents, as disclosed by X-ray diffraction and theoretical studies.