Cyclometalated Half-Sandwich Ruthenium Complexes: Preparation, Structure, and Catalytic Synthesis of Phenolic Esters from Aryl Halides without Using External CO under Air.

A series of cyclometalated C,N-chelate half-sandwich ruthenium complexes based on N-heterocyclic ligands were prepared through a simple route with good yields. These air- and moisture-stable cyclometalated ruthenium complexes showed excellent catalytic efficiency in phenoxy carbonylation of aryl halides with phenyl formate derivatives as a CO source and phenol as a coupling partner under air. Ester products were obtained with high yields at room temperature and without the need for an inert atmosphere. The excellent catalytic activity, broad substrate range, and mild reaction conditions made this catalytic system potential for industrial production. In addition, DFT study has been carried out to elaborate the possible mechanism of this Ru-catalyzed reaction.

Half-Sandwich Iridium Complexes Based on ß-Ketoamino Ligands: Preparation, Structure, and Catalytic Activity in Amide Synthesis.

A series of ß-ketoamino-based N,O-chelate half-sandwich iridium complexes with the general formula [Cp*IrClL] have been prepared in good yields. These air-insensitive iridium complexes showed desirable catalytic activity in an amide preparation under mild conditions. A number of amides with diverse substituted groups were furnished in a one-pot reaction with good-to-excellent yields through an amidation reaction of NH2OH·HCl with aldehydes in the presence of these iridium(III) precursors. The excellent catalytic activity, mild reaction conditions, and broad substrate scope gave this type of iridium catalyst potential for use in industry. All of the obtained iridium complexes were well characterized by different spectroscopy techniques. The exact molecular structure of complex 3 has been confirmed by single-crystal X-ray analysis.