Understanding the interactions of diruthenium anticancer agents with amino acids.

The dinuclear anticancer agents 1,n-bis{chlorido[3-(oxo-κO)-2-methyl-4-(1H)-pyridinonato-κO4](η6-p-cymene)-ruthenium(II)}alkane (PyRu 2n ) exhibit high antiproliferative activity in human cancer cell. Reactivity studies with DNA and protein revealed uncommon protein-DNA and DNA-DNA crosslinking ability. We report here studies on the reactions of the diruthenium organometallics PyRu 26 and PyRu 28 in comparison with a mononuclear analogue PyRu3 with amino acids using mass spectrometry and NMR spectroscopy. The compounds behave very similarly, independent of the spacer length between the metal center and of the nuclearity of the complexes. Incubation with L-cysteine (Cys) results in fast release of the pyridone ligand, with the Ru complexes able to form Cys adducts. In contrast, L-methionine forms, initially, adducts with the metal centers, but over time, the adducts decompose. Similar behavior was observed for the reaction with L-histidine with [Ru(η6-p-cymene)(L-histidine)] species detected.

The hydration of chloroacetonitriles catalyzed by mono- and dinuclear Ru(II)- and Os(II)-arene complexes.

The hydration of nitriles to the corresponding amides is an important reaction for both laboratory and industry purposes. The classical synthesis method requires harsh conditions, gives low yields, and is nonselective due to further hydrolysis of the amides into carboxylic acids. To obtain good yields and high selectivity, transition metal complexes have been utilized as catalysts for this transformation. Herein, a series of Ru(II)- and Os(II)-arene complexes--based on pyranone, thiopyranone, and pyridinone ligands--were assayed on the hydration of chloroacetonitriles. The influence of the substitution pattern of the ligand, and of the nuclearity and of the type of substrate on the yield, the selectivity, and the turnover numbers are discussed.