All-Metal Aromatic Cationic Palladium Triangles Can Mimic Aromatic Donor Ligands towards Lewis Acidic Cations

We present that cationic rings could act as donor ligands thanks to suitably delocalized metal-metal bonds. This could grant to parent complexes the peculiar properties of aromatic rings crafted with main group elements. We assembled Pd nuclei into equilateral mono-cationic triangles with unhindered faces. Like their main-group element counterparts and despite their positive charge, these noble-metal rings form stable bonding interactions with other cations, as positively charged silver atoms, delivering the corresponding tetranuclear dicationic complexes. Through a mix of modeling and experimental techniques we propose that this bonding mode is an original coordination-like one rather than a 4-centres-2-electrons bond, which were already observed in three dimensional aromatics. Present results thus opens the way to the use of suitable metal rings as ligands for coordination chemistry and catalysis