Complexes of doubly chelating ligands. Part III. Proton and copper(II) complexes of 3,4-dihydroxyphenylglycine (DOPG)

Abstract

The four acid dissociation constants of the 3,4-dihydroxyphenylglycine (DOPG) cation have been determined at 25°± 0·01° and 1·0M ionic strength (KNO₃) by means of a glass-calomel electrode system. The reactions of the ligand with copper(II) ions were also examined by pH methods; polymer formation and ligand exchange reactions have been observed and the behaviour of this system compared with reactions of related ligands. Stability constants for the copper complexes and for the formation of a tetramer are reported.