Ligand-Exchange-Induced Growth of an Atomically Precise Cu₂₉ Nanocluster from a Smaller Cluster

Abstract

The copper hydride nanocluster (NC) [Cu29Cl4H22(Ph2phen)12]Cl (2; Ph2phen = 4,7-diphenyl-1,10-phenanthroline) was isolated cleanly, and in good yields, by controlled growth from the smaller NC, [Cu25H22(PPh3)12]Cl (1), in the presence of Ph2phen and a chloride source at room temperature. Complex 2 was fully characterized by single-crystal X-ray diffraction, XANES, and XPS, and represents a rare example of an N* = 2 superatom. Its formation from 1 demonstrates that atomically precise copper clusters can be used as templates to generate larger NCs that retain the fundamental electronic and bonding properties of the original cluster. A time-resolved kinetic evaluation of the formation of 2 reveals that the mechanism of cluster growth is initiated by rapid ligand exchange. The slower extrusion of CuCl monomer, its transport, and subsequent capture by intact clusters resemble elementary steps in the reactant-assisted Ostwald ripening of metal nanoparticles.