EFFECTS OF N-SUBSTITUENTS AND C-SUBSTITUENTS ON PROTONATION OF 14-MEMBERED TETRAAZA MACROCYCLES AND FORMATION OF THEIR COPPER(II) AND NICKEL(II) COMPLEXES

The protonation constants of the 14-membered tetraaza macrocycles A(3,14-dimethyl-2,6,13,17-tetraazatricyclo[16.4.0(1.18). 0(7.12)]docosane) and B(2,3,6,13,14,17-hexamethyl-2,6,13,17-tetraazatricyclo-[16.4.0(1.18).0(7.12)] docosane) were measured by potentiometry. The formation constants of each of these ligands with copper(II) and nickel(II) were determined by an out-of-cell spectrophotometric method. The results indicate that the per-N-methylated macrocycle B exhibits much higher selectivity for complex formation with copper(II) over nickel(II) ion than A and other related 14-membered tetraaza macrocycles The effects of the N-and C-substituents on the basicity and the metal ion selectivity of the ligands are discussed. The synthesis and properties of copper(II) and nickel(II) complexes of B are also described.