Synergistic coordination of diphosphine with primary and tertiary phosphorus centers: Ultrastable icosidodecahedral Ag 30 nanoclusters with metallic aromaticity

As versatile ligands with extraordinary coordination capabilities, RPH 2 (R = alkyl or aryl) are rarely used in constructing metal nanoclusters due to their volatility, toxicity, spontaneous flammability, and susceptibility to oxidation. In this work, we designed a primary and tertiary phosphorus-bound diphosphine chelator (2-Ph 2 PC 6 H 4 PH 2 ) to create ultrastable silver nanoclusters with metallic aromaticity. By controlling the deprotonation rate of 2-Ph 2 PC 6 H 4 PH 2 and adjusting the templates, we successfully synthesized two near-infrared emissive nanoclusters, Ag30 and Ag32 , which have analogous icosidodecahedral Ag 30 shells with an I h symmetry. Deprotonated ligand (2-Ph 2 P α C 6 H 4 P β 2− ) exhibits a coordination mode of μ 5 -η 1 (P β ),η 2 (P α ,P β ), which endows a unique metallic aromaticity to Ag30 and Ag32 . The solution-processed organic light-emitting diodes based on Ag30 achieve an external quantum efficiency of 15.1%, representing the breakthrough in application of silver nanoclusters to near-infrared–emitting devices. This work represents a special ligand system for synthesizing ligand-protected coinage metal nanoclusters and opens up horizons of creating nanoclusters with distinct geometries and metal aromaticity.