Homo and hetero dioxygen complexes of Co(II), Cu(II), Ni(II) and Pb(II) with the ligand 3,7,11,19,23,27-hexaaza-33,34-dihydroxy-15,31-dimethyltricyclotetratriaconta-1(32),13,15,17(34),29(33),30-hexaene

In this paper the oxygenation of HDTHCo homo and heterodinuclear complexes with Cu(II), Ni(II) and Pb(II) in aqueous solution by control of the stoichiometry of metal ions and HDTH as well as p[H] of solution was investigated (HDTH is a dinucleating 28-membered hexaazadiphenol macrocyclic ligand, 3,7,11,19,23,27-hexaaza-33,34-dihydroxy-15,31-dimethyl-tricyclo-tetratriaconta-1(32),13,15,17(34),29(33),30-hexaene). The pH potentiometric method was utilized successfully to determine oxygenation constants and to determine the distribution of species present in the solution as a function of p[H]. Spectrophotometry was used to investigate the oxygenation process of the homo and heterodinuclear complexes. The X-ray crystal structure of homodinuclear complexes of Ni(II) is also reported. These studies suggested autooxidation takes place during the oxygenation of homo and heterodinuclear Co(II) complexes of the macrocyclic ligand. The neighboring effect increases in the order Ni(II)