Synthesis of Trimetallic (HPd@M₂Au₈)³⁺ Superatoms (M = Ag, Cu) via Hydride-Mediated Regioselective Doping to (Pd@Au₈)²⁺

We have recently reported that hydride (H^–) doped superatom (HPd@Au₈)⁺ protected by eight PPh₃ ligands selectively grew into (HPd@Au₁₀)³⁺ by the nucleophilic addition of two Au­(I)Cl units. In the present study, (HPd@Au₈)⁺ was successfully converted to unprecedented trimetallic (HPd@M₂Au₈)³⁺ superatoms (M = Ag, Cu) by controlled doping of two Ag­(I)­Cl or Cu­(I)Cl units, respectively. Single-crystal X-ray diffraction analysis demonstrated that two Ag­(I) or Cu­(I) ions were regioselectively incorporated. Theoretical calculations suggested that hydrogens in (HPd@M₂Au₈)³⁺ (M = Au, Ag, Cu) occupy the same bridging site between the central Pd atom and the surface Au atom. (HPd@Ag₂Au₈)³⁺ exhibited photoluminescence at 775 nm, with the enhanced quantum yield of 0.09%, although it is structurally and electronically equivalent with (HPd@Au₁₀)³⁺. This study demonstrates that hydride-mediated growth process is a promising atomically-precise bottom-up synthetic method of new multimetallic superatoms.