Controlling\nthe Size of Molecular Copper Clusters\nSupported by a Multinucleating Macrocycle

The use of a nonrigid, pyridyldialdimine-derived macrocyclic\nligand\n(<sup>3</sup>PDAI<sub>2</sub>) enabled the synthesis of well-defined\nmono-, di-, tri-, and tetra-nuclear Cu(I) complexes in good yields\nthrough rational synthetic means. Starting from mono- and diargentous <sup>3</sup>PDAI<sub>2</sub> complexes, transmetalation to Cu(I) proceeded\nsmoothly with formation of AgX (X = Cl, I) salts to generate mono-,\ndi-, and trinuclear copper complexes. Monodentate supporting ligands\n(MeCN, xylNC, PMe<sub>3</sub>, PPh<sub>3</sub>) were found to either\ntransmetallate with or bind various di- and trinuclear clusters. The\nsolution-phase dynamic behaviors of these species were studied through\nNMR spectroscopic investigations, and an in-depth study of the trinuclear\nsystems revealed a rate dependence on the identity of the supporting\nligand, indicating that ligand dissociation reactions were involved\nin the dynamic exchange processes. Synthetic investigations further\nfound methods for the purposeful interconversion between the di- and\ntrinuclear systems as well as the synthesis of a pseudotetrahedral\ntetracopper complex with two μ-Ph supporting ligands.