Schiff Base Ligand And Trimethylphosphine Ligand Acyl Cobalt (iii) Hydride The Reaction Performance

Cobalt belongs to VIII family of transition metals. Because of its fine coordination activity and relatively low price, it has been widely used in organic synthesis, industrial catalysis, etc. Transition metal has a great affinity for trivalent phosphine, with which stable complexes will engender, can make M-C bond much more stable. Moreover, by transforming the category and structure of phosophine ligand, we can often regulate the activity and selectivity of homogeneous catalyst. Therefore, it occupies an important place in organic chemistry. The organometallic compound of cobalt coordinated with trimethylphosphine has high reaction activity and selectivity. Acyl(hydrido)cobalt (â…¢) complexes, which are stabilized by a (2-acyl)-phenolato chelating ligand and supporting trimethylphosphine, synthesized in the ninties of the twentieth century, react with different compounds.Schiff-base is widely used in industrial chemical production and scientific research as chelating agent, stabilizer, bioactivator, analytical reagent and catalyzer etc. Complexes formed by cobalt with Shiff-base ligands have good catalysis activity. The study of this domain has been a hotspot in the fields of coordination chemistry and organometallic chemistry for recent years.This thesis seeks to discuss the influence of the electronic effect of shiff-base ligands to their reactions with acyl(hydrido)cobalt (â…¢) complexes. By this experiment (2- imido)phenolatocobalt(â…¢) complexes with a 2-acylphenolato chelating ligand as co-ligand (16-21) were synthesized as expected product, and the side-product bis(2-imido-phenolato)cobalt(â…¡) was also obtained. The first step in the proposed mechanism consists of a substitution of the coordinated phenoxy group of the 2-acylphenolato chelating ligand by that of a (2- imido)phenolato chelating ligand which affords an intermediate of cobalt(â… ) complex. The (2- imido)phenolatocobalt(â… ) complex disproportionates to bis(2-imido-phenolato)cobalt(â…¡) and cobalt(0) complex. In a parallel reaction the hydridocobalt complex reacts with schiff-base under participation of regenerated aldehyde to afford the bis-chelate complex and simultaneously the aldehyde is reduced to a alcohol by liberated H₂. According to the...