The stoichiometries and stability constants of the complexes formed in the manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II)-L-adrenaline and noradrenaline systems were determined pH-metrically at 25 °C and 0.2 mol/dm3 ionic strength. It was proved that when there is an excess of ligand only the ortho hydroxy groups take part in the coordination, and that the participation of the side-chain in the complex formation is subordinate. From an ESR spectral study of the copper(II)-adrenaline system it was assumed that at a metal ion/ligand ratio of 1:1 and at higher pH (pH > 10) a polynuclear complex may also be formed. In this species the mode of bonding is mixed, with the participation of the side-chain donor groups. It was found that the complex-forming properties of adrenaline and noradrenaline towards the transition metal ions studied are very similar, this being a consequence of the small difference between the structures of these ligands.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry