Stabelity of mixed ligand complexes of copper(II): ESR studies

Abstract

Three new mixed ligand complexes of Cu(II) obtained by combining any two of the three ligands, diethyldithiocarbamate, N-benzoyl-N′-diethylthiocarbamide and acetylacetonate have been identified in reaction mixtures using electron spin resonance (esr), by estimating the equilibrium constantK associated with the ligand exchange reaction. TheK values were also determined for fifteen other mixed ligand complexes of Cu(II) reported earlier. The stability of these mixed ligand complexes was correlated with the difference in the strengths of covalent bonding between the metal ion and the two ligands. The bondings involving both the $$d_{x^2 } - _{y^2 } $$ andd xy orbitals on the metal were necessary. In addition, the extent of metal 4s-orbital mixed in the unpaired electron orbital contributed to the magnitude ofK. The diagrams similar to the ones used in our correlation could be useful in predicting the probable yield of mixed ligand complexes in reaction mixtures.