Kinetic Versus Thermodynamic Metalation Enables Synthesis of Isostructural Homo- and Heterometallic Trinuclear Clusters

Temperature-dependent metalation of the new hexadentate ligand (tris(5-(pyridin-2-yl)-1H-pyrrol-2-yl)methane; H₃TPM) enables the selective synthesis of both mononuclear (i.e. Na(THF)₄[Fe(TPM)], kinetic product) and trinuclear (i.e. Fe₃(TPM)₂, thermodynamic product) complexes. Exposure of Na(THF)₄[Fe(TPM)] to FeCl₂ or ZnCl₂ triggers cluster expansion to generate homo- or heterometallic trinuclear complexes, respectively. The developed approach enables systematic variation of ion content in isostructural metal clusters via programmed assembly.