Kumada-Corriu Cross-Coupling Reaction Catalyzed by Cobalt Nanoparticles Arising from the Reductive Decomposition of a Cobaltacycle

This study shows that the nanoparticles produced by the reductive decomposition of a cobalt (+III) metallacycle derived from 2-phenylpyridine upon treatment with the highly nucleophilic Na[Et3BH] are capable of promoting the Kumada-Corriu cross coupling of aryl halides with aryl-bromomagnesium compounds (Grignard reagents) in various conditions and in the presence of various stabilizing ligands to afford the non-symmetric organic bisaryl product in reasonable yields. This study provides further evidence that incidental Co nanoparticles possess a reasonable capability in homogeneous catalysis, thereby complementing a prior report on their ability to promote the hydrosilylation of unsaturated organic substrates, such as nitriles. Co nanoparticles were characterized by HRTEM, EDX, EELS, and SAED techniques. TEM analyses revealed that the nanoparticles were uniformly spherical in shape, with a narrow size distribution; no nanoparticles larger than 3 nm were observed. EDX analysis displaying a characteristic Co signature at about 7 keV. The magnetic behavior of the nanoparticles studied by SQUID analysis in toluene using a temperature varied from 2 to 300 K, and a low magnetic field (10-3T) in ZFC-FC conditions.