Synergistic coordination of diphosphine with primary and tertiary phosphorus centers: Ultrastable icosidodecahedral Ag30 nanoclusters with metallic aromaticity.

Abstract

As versatile ligands with extraordinary coordination capabilities, RPH₂ (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-Ph₂PC₆H₄PH₂) to create ultrastable silver nanoclusters with metallic aromaticity. By controlling the deprotonation rate of 2-Ph₂PC₆H₄PH₂ and adjusting the templates, we successfully synthesized two near-infrared emissive nanoclusters, Ag30 and Ag32, which have analogous icosidodecahedral Ag₃₀ shells with an I_h symmetry. Deprotonated ligand (2-Ph₂P_αC₆H₄P_β^2-) exhibits a coordination mode of μ₅-η¹(P_β),η²(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.