The Stability of Fused Rings in Metal Chelates. IV. Preparation and Relative Stability of Copper(II) Complexes with Tetradentate Schiff Base Ligands

Relative stability of sixteen aldehyde- and the corresponding ketone-Schiff base chelates has been investigated in terms of their decomposing temperature and half-wave potential against the reduction of copper(II) at the dropping mercury electrode. The previous conclusion, established for copper(II) tridentate Schiff base complexes, that Schiff base chelates of aldehydes are generally less stable than those of corresponding ketones has been proved to be valid also for copper(II) tetradentate Schiff base complexes if there is no serious steric hindrance in the Schiff base ligand. As a result of this investigation, six new copper(II) chelates were synthesized and characterized.