Question

What is the purpose or objective of the synthesis of CoII(salen) complex?

Answer 1

Biologically active metal centers are very often found in a coordination environment that includes multidentate ligands. Therefore the synthesis of bioinorganic model complexes often makes use of multidentate ligands that resemble those found in nature. Multidentate ligand used in the synthesis of Co(II) salen complex is tetradentate N,N’-bis(salicylaldehyde)-ethylenediimine (it is abbreviates as salenH₂). It is obtained by the condensation reaction shown below:

In the synthesis process, we will prepare salenH₂, and its complex with Co(II), Co(salen), as a mixture of the brown and dark red forms. This mixture is heated to accomplish complete conversion to the dark red form. The experiment will be conducted in chloroform and DMSO solvents. DMSO is a good ligand for transition metals. The mixture is dissolved in DMSO in a closed system containing pure oxygen to generate an active form. The oxygen uptake is quantitatively measured at constant temperature and pressure. The oxygen adduct is then dissolved in chloroform to release the oxygen.