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

Aurophilic interaction plays a very important role in gold-related clusters. Here, we investigate the Au n Cl n +1 - ( n = 1-7) cluster ions using Fourier transform ion cyclotron resonance mass spectrometry in combination with theoretical calculations. Three cluster ions of Au 2 Cl 3 - , Au 3 Cl 4 - , and Au 4 Cl 5 - show their remarkable intensities in the mass spectrum. Geometric structure optimizations for Au n Cl n +1 - ( n = 1-7) were performed on the MP2 level. The results show that the most stable structures of Au n Cl n +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 Au 6 Cl 7 - and Au 7 Cl 8 - , whereas the aurophilic interactions between nonterminal adjacent gold atoms stabilize at n = 5.