Stable ruthenium indenylidene complexes with a sterically reduced NHC ligand.

Stable and active Ru olefin metathesis catalyst 7 bearing a sterically reduced NHC ligand was synthesized. Upon action of pyridine, 7 forms complex 24, the first example of an Ru–indenylidene catalyst bearing a labile pyridine ligand and a sterically less demanding NHC ligand.

Iron-catalyzed hydrogen production from formic acid.

Hydrogen represents a clean energy source, which can be efficiently used in fuel cells generating electricity with water as the only byproduct. However, hydrogen generation from renewables under mild conditions and efficient hydrogen storage in a safe and reversible manner constitute important challenges. In this respect formic acid (HCO(2)H) represents a convenient hydrogen storage material, because it is one of the major products from biomass and can undergo selective decomposition to hydrogen and carbon dioxide in the presence of suitable catalysts.

Efficient palladium-catalyzed coupling reactions of aryl bromides and chlorides with phenols.

A convenient and general palladium-catalyzed coupling reaction of aryl bromides and chlorides with phenols was developed. Various functional groups such as nitriles, aldehydes, ketones and esters are well tolerated and the corresponding products are obtained in good to excellent yield.

A general palladium-catalyzed amination of aryl halides with ammonia.

A new robust palladium/phosphine catalyst system for the selective monoarylation of ammonia with different aryl bromides and chlorides has been developed. The active catalyst is formed in situ from [Pd(OAc)(2)] and air- and moisture-stable phosphines as easy-to-handle pre-catalysts. The productivity of the catalyst system is comparable to that of competitive Pd/phosphine systems; full conversion is achieved with most substrates with 1-2 mol % of Pd source and a fourfold excess of ligand (L).

Palladium catalysts for highly selective Sonogashira reactions of aryl and heteroaryl bromides.

Palladium catalysts have been studied for the Sonogashira-Hagihara coupling of aryl and heteroaryl bromides with terminal alkynes. Among the different biarylphosphines tested, 2-(di-tert-butylphosphino)-N-phenylindole (cataCXium Plntb) allows the efficient coupling of both activated and deactivated (hetero)aryl bromides in the presence of sodium tetrachloropalladate in tetramethylethylenediamine (TMEDA) at 80 degrees C. The catalyst system gives high turnover numbers (up to 14 100) and shows a broad tolerance towards functional groups such as OH and NH2, as well as heterocycles.