Update on metal N-heterocyclic carbene complexes as potential anti-tumor metallodrugs

The clinical success of platinum-based chemotherapeutic agents was of enormous impact on the discovery of novel metal N-heterocyclic carbene (NHC) complexes as potential anti-cancer drugs. During the last years, the research on cytotoxic transition metal (e.g. Ag, Au, Pt, Pd, Cu, Hg, Ru, Os, Rh and Ir) NHC complexes was successful and the results are remarkable. In this review, we provide an update on the recent advances in this direction, which reflects new discoveries since the publication of our previous review. The anti-tumor properties along with the mechanisms of action for these complexes as well as possible structure-activity relationships are discussed.