Indazolin‑<i>s</i>‑ylidene–N-Heterocyclic Carbene Complexes of Rhodium, Palladium, and Gold: Synthesis, Characterization, and Catalytic Hydration of Alkynes

A novel series of Indy-N-heterocyclic carbene ligands (Indy = indazolin-<i>s</i>-ylidene) have been developed and investigated. Via a mild Ag carbene transfer route, these new carbene ligands reacted with rhodium, palladium, and gold salts to yield the corresponding air-stable metal complexes. The product complexes were characterized by NMR spectroscopic methods and X-ray diffraction analysis. The electronic properties of these complexes were modified by the introduction of different substituents at the coordinated NHC ligands. Catalytic properties of the gold complex were evaluated in the hydration of alkynes to give the corresponding ketone products. This new type of gold N-heterocyclic carbene complex showed a high catalytic activity in the hydration of alkyne at room temperature

Indazolin‑<i>s</i>‑ylidene–N-Heterocyclic Carbene Complexes of Rhodium, Palladium, and Gold: Synthesis, Characterization, and Catalytic Hydration of Alkynes

A novel series of Indy-N-heterocyclic carbene ligands (Indy = indazolin-<i>s</i>-ylidene) have been developed and investigated. Via a mild Ag carbene transfer route, these new carbene ligands reacted with rhodium, palladium, and gold salts to yield the corresponding air-stable metal complexes. The product complexes were characterized by NMR spectroscopic methods and X-ray diffraction analysis. The electronic properties of these complexes were modified by the introduction of different substituents at the coordinated NHC ligands. Catalytic properties of the gold complex were evaluated in the hydration of alkynes to give the corresponding ketone products. This new type of gold N-heterocyclic carbene complex showed a high catalytic activity in the hydration of alkyne at room temperature

Activation of C–H Bonds in Nitrones Leads to Iridium Hydrides with Antitumor Activity

We report the design and synthesis of a series of new cyclometalated iridium hydrides derived from the C–H bond activation of aromatic nitrones and the biological evaluation of these iridium hydrides as antitumor agents. The nitrone ligands are based on the structure of a popular antioxidant, α-phenyl-<i>N</i>-<i>tert</i>-butylnitrone (PBN). Compared to cisplatin, the iridium hydrides exhibit excellent antitumor activity on HepG2 cells. The metal-coordinated compound with the most potent anticancer activity, <b>2f</b>, was selected for further analysis because of its ability to induce apoptosis and interact with DNA. During in vitro studies and in vivo efficacy analysis with tumor xenograft models in Institute of Cancer Research (ICR) mice, complex <b>2f</b> exhibited antitumor activity that was markedly superior to that of cisplatin. Our results suggest, for the first time, that metal hydrides could be a new type of metal-based antitumor agent