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.

Laser ablation mass spectrometry was applied to study the cluster anions of Pt 2 Cl n − . Among them, Pt 2 Cl 6 − and Pt 2 Cl 9 − were observed with remarkable intensities in the mass spectrum. Collision-activated dissociation experiments were also performed for the two anions. A systematic study of the structures and electron affinities (EAs) of Pt 1−2 Cl n (2 ≤ n ≤ 10) clusters was performed on the level of B3LYP/Lanl2dz/6-311++G(2d, p). For both systems, their EAs do not increase monotonically with the increase of Cl atoms. All the clusters of PtCl n (3 ≤ n ≤ 10) and Pt 2 Cl n (3 ≤ n ≤ 10) show EAs larger than that of the Cl atom. The highest EAs for the series of Pt 2 Cl n and PtCl n are 6.55 and 5.82 eV, corresponding to those of Pt 2 Cl 9 and PtCl 9 , respectively. The results indicate that these clusters might be applied as effective units in constructing new "hypersalts".

Negative ion mass spectrometry can serve as an effective and easy way to find new candidates of superhalogen species. In order to investigate superhalogen properties of polytitanium clusters, the laser ablation mass spectrum of TiO2 was obtained with a Fourier transform ion cyclotron resonance mass spectrometer. Density functional theory calculations were also performed in this study. Species of [(TiO2) x (H2O) y OH]− (x = 1–8, y = 1–3) were observed in the mass spectrum. Among them, the intensities of [(TiO2)4(H2O)­OH]−, [(TiO2)4(H2O)2OH]−, [(TiO2)3(H2O)2OH]−, and [(TiO2)5(H2O)2OH]− are remarkable. The structures of these species and their neutral counterparts are studied on the level of B3LYP/Lanl2dz/6-311++G­(2d, 2p). Results show that the electron affinities (EAs) of the neutral clusters are all higher than that of the chlorine atom and (TiO2)4(H2O)2OH has the highest electron affinity value at 6.23 eV. This series of polytitanium superhalogens not only indicate that the OH might be applied as an effective superhalogen ligand but also show the potential of metal titanium in the design of novel superhalogen compounds.

Au2nCl– (n = 1–4) clusters are investigated by both laser ablation mass spectrometry and theoretical calculations. It is interesting to find that the electron affinities of neutral Au2nCl (n = 1–4) clusters are much larger than those of corresponding pure Au2n clusters. Among them, the electron affinity of Au2Cl is 4.02 eV, which can be defined as a very unique superhalogen that is quite different from classical ones of MnXm (M = metal, X = halogen, and n < m). Natural bond orbital and highest occupied molecular orbital analyses indicate that the extra electron is predominantly delocalized over the positively charged metal moiety in these anionic Au2nCl– clusters, which is the main reason for the large electron affinities of the corresponding neutral species.