Structure of gold-oxo nanoclusters in solution

The properties of the two know polyoxoaurates in [Au₄As₄O₂₀]^8– and  [Au₄Se₄O₁₆]^4– were recently studied in a combined experimental and theoretical effort. Through combining electrospray ionization mass spectrometry (ESI-MS) and UV/VIS spectroscopy and analysis with relativistic TDDFT calculations with ADF, the structure of the polyanions in solution was elucidated. TDDFT, corroborated by ESI-MS experiments, suggest that while [Au₄As₄O₂₀]^8– is bare in solution, the arsenate oxoaurate is best described by a dimer [Na₅Au₈As₈O₄₀]^11–, very similar to its solid state structure.

Experimental spectrum of [Au₄As₄O₂₀]^8– in solution compared to calculated spectrum (TDDFT, M06/ZORA-SR/TZP/COSMO)

A. Kondinski, N. Vankova, F. Schinle, P. Jaeger, O. Hampe, U. Kortz and T. Heine, How Counterions Affect the Solution Structure of Polyoxoaurates: Insights from UV/Vis Spectral Simulations and Electrospray Mass Spectrometry Eur. J. Inorg. Chem. 2014, 3771-3778.