Figure 3. UV/Vis spectra of all three Au 32 clusters 1 Et (blue), 1 Pr (orange), and 1 Bu (green) in dichloromethane. The spectra show one clear band at 480 nm, three weak bands at 600, 662, and 727 nm, and five shoulders at 395, 448, 510, 538, and 565 nm. Angewandte ChemieCommunications 5904 www.angewandte.org

The reduction of (Ph P)AuCl with NaBH in the presence of HSC(SiMe ) , leads to one of the largest metalloid gold clusters: Au S (PPh ) (1). Within 1 an octahedral Au core of gold atoms arranged as in Au metal is surrounded by 48 oxidized Au atoms of an Au S shell, a novel building block in gold chemistry. The protecting Au S shell is completed by additional 16 Au(PPh ) units, leading to a complete protection of the gold core. Within 1 the Au-Au distances get more molecular on going from the center to the ligand shell. Cluster 1 represents novel structural motives in the field of metalloid gold clusters which also are partly typical for metal atoms in metalloid clusters: M R (n>m).

Reducing (PhP)AuSC(SiMe) with l-Selectride® gives the medium-sized metalloid gold cluster AuS(PPh). Computational studies show that the phosphine bound Au-atoms not only stabilize the electronic structure of AuS(PPh), but also behave as electron acceptors leading to auride-like gold atoms on the exterior.

Gold chemistry and the synthesis of colloidal gold always caught the attention of scientists. This review depicts the development of the chemistry of metalloid gold clusters over the last few decades and shows recent scientific developments.