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

Bimetallic nanoclusters Au19Cu30 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 Au19Cu30 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 Au19Cu30 represents the first alkynyl-protected Au-Cu alloy nanocluster.