Atomically Precise Bimetallic Au₁₉Cu₃₀ Nanocluster with an Icosidodecahedral Cu₃₀ Shell and an Alkynyl–Cu Interface

Bimetallic nanoclusters <b>Au</b>_<b>19</b><b>Cu</b>_<b>30</b> with chemical composition of [Au₁₉Cu₃₀(CCR)₂₂(Ph₃P)₆Cl₂]­(NO₃)₃ (where RCC is from 3-ethynylthiophene (H₃C₄S-3CCH) or ethynylbenzene (PhCCH)) has been synthesized. Single X-ray structural analysis reveals that <b>Au</b>_<b>19</b><b>Cu</b>_<b>30</b> has a multishelled core structure of Au@Au₁₂@Cu₃₀@Au₆, comprising a centered icosahedral Au₁₃ (Au@Au₁₂) surrounded by an icosidodecahedral Cu₃₀ shell and an outmost shell of a chairlike hexagonal Au₆. The alkynyl carbon is bound to the hollow sites on the Au₁₉Cu₃₀ nanocluster surface, which is a novel interfacial binding mode in alkynyl-protected alloy nanoclusters. The Cu₃₀ icosidodecahedron is unprecedented and <b>Au</b>_<b>19</b><b>Cu</b>_<b>30</b> represents the first alkynyl-protected Au–Cu alloy nanocluster