Crystal Structure, Electrochemical and Optical Properties of [Au9(PPh3)8](NO3)3

The single‐crystal structure of [Au9(PPh3)8](NO3)3 was resolved for the first time with atomic resolution. The cluster has crystallographic D2 and approximate molecular D2h skeletal symmetry derived from an icosahedron. Voltammetry of the Au9 clusters in CH2Cl2 reveals a 1.78‐eV energy gap between the first one‐electron oxidation peak and the first reduction peak. The UV/Vis and luminescence properties of Au9 clusters were also investigated. The cluster solid shows two broad emission peaks at 579 nm and 853 nm, respectively, at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)