Ruthenium compounds as anticancer agents

For half a century, the field of metal-based anticancer drugs has been dominated by the precious metal platinum. The discovery of platinum's anticancer properties was made by chance during an experiment in 1965, conducted at Michigan State University by Barnett Rosenberg. Rosenberg used a platinum electrode to apply an electric field to a colony of E. coli,  which was observed to inhibit their growth. A diligent investigation into the cause of this effect concluded that the platinum electrode was breaking down to generate platinum(II) species in situ,  which was stopping the cells from multiplying. 

This observation led to cis-diamminedichloroplatinum(II), commonly known as cisplatin, being approved by the American Food and Drugs Administration (FDA) for cancer therapy in 1978. It has since become the most widely used anticancer drug, with an estimated 70% of patients receiving the compound as part of their treatment.¹