Atomically Precise Bimetallic AuCu Nanocluster with an Icosidodecahedral Cu Shell and an Alkynyl-Cu Interface.

Bimetallic nanoclusters AuCu with chemical composition of [AuCu(C≡CR)(PhP)Cl](NO) (where RC≡C is from 3-ethynylthiophene (HCS-3-C≡CH) or ethynylbenzene (PhC≡CH)) has been synthesized. Single X-ray structural analysis reveals that AuCu has a multishelled core structure of Au@Au@Cu@Au, comprising a centered icosahedral Au (Au@Au) surrounded by an icosidodecahedral Cu shell and an outmost shell of a chairlike hexagonal Au. The alkynyl carbon is bound to the hollow sites on the AuCu nanocluster surface, which is a novel interfacial binding mode in alkynyl-protected alloy nanoclusters. The Cu icosidodecahedron is unprecedented and AuCu represents the first alkynyl-protected Au-Cu alloy nanocluster.