Synthesis and characterization of high-nuclearity Rh-Au clusters stabilized by carbonyl ligands

The aim of this project was to synthesize and characterize new high nuclearity heterometallic Rh-Au clusters. The reactivity of rhodium clusters was studied starting from the precursor [Rh7(CO)16]3-, which was oxidated with different Au3+ and Au+ salts. Its behaviour was analysed in different reaction conditions, changing each time the Rh:Au stoichiometric ratio and solvents, under controlled CO atmosphere. Multiple new clusters were obtained: [Rh10Au(CO)26]3-, [Rh16Au6(CO)36]4-, [Rh19Au5(CO)40]4- and [Rh20Au7(CO)45]5-. A clean and reproducible synthetic pathway to synthesize the new [Rh10Au(CO)26]3- was discovered. Moreover, a new synthetic pathway to synthetize [Rh16Au6(CO)36]6- was discovered. Each compound has been characterized via FT-IR spectroscopy and single crystal X-ray diffractometry; [Rh10Au(CO)26]3-, [Rh16Au6(CO)36]4- and [Rh16Au6(CO)36]6- have been also analysed via ESI-MS analysis. Finally, chemical reactivity tests on [Rh10Au(CO)26]3- were conducted, verifying that a consecutive pathway starting from the latter leads to the formation of [Rh16Au6(CO)36]4-.