Size Effect on Aurophilic Interaction in Gold-Chloride Cluster Anions of AunCln+1- (2 ≤ n ≤ 7)

Abstract

Aurophilic interaction plays a very important role in gold-related clusters. Here, we investigate the AunCln+1- (n = 1-7) cluster ions using Fourier transform ion cyclotron resonance mass spectrometry in combination with theoretical calculations. Three cluster ions of Au2Cl3-, Au3Cl4-, and Au4Cl5- show their remarkable intensities in the mass spectrum. Geometric structure optimizations for AunCln+1- (n = 1-7) were performed on the MP2 level. The results show that the most stable structures of AunCln+1- (n = 2-7) are all characterized by a zigzag structure. Furthermore, it can be found that the aurophilic interactions containing terminal gold atoms strengthen with the increase of total gold atoms and progressively stabilize for large clusters of Au6Cl7- and Au7Cl8-, whereas the aurophilic interactions between nonterminal adjacent gold atoms stabilize at n = 5.