Structural Isomerism in Bimetallic AgCu Nanoclusters.

Structural isomers of atomically precise metal nanoclusters are highly sought after for investigating structure-property relationships in nanostructured materials. However, they are extremely rare, particularly those of alloys, primarily due to the challenges in their synthesis and structural characterization. Herein, for the first time, a pair of bimetallic isomeric AgCu nanoclusters has been controllably synthesized and structurally characterized. These two isomers share an identical molecular formula, AgCu(C≡CR) (denoted as and ; HC≡CR is 3,5-bis(trifluoromethyl)phenylacetylene). Single-crystal X-ray diffraction data analysis revealed that possesses an AgCu core composed of two interpenetrating hollow AgCu structures. This core is stabilized by four different types of surface motifs: eight -C≡CR, one Cu(C≡CR), one AgCu(C≡CR), and two Cu(C≡CR) units. features a bitetrahedron Ag core, which is stabilized by three AgCu(C≡CR) units. Interestingly, undergoes spontaneous transformation to in the solution-state. Density functional theory calculations explain the electronic and optical properties and confirm the higher relative stability of compared to . The controlled synthesis and structural isomerism of alloy nanoclusters presented in this work will stimulate and broaden research on nanoscale isomerism.