Properties of N,N-dimethyl-N′-(2-hydroxybenzyl)ethylenediamine as a ligand to copper(II)

The acid-basic and complexing properties of N,N-dimethyl-N'-(2-hydroxybenzyl)ethylenediamine (HL) in aqueous propan-2-ol were characterized by spectrophotometry, pH-metry, and mathematical simulation of equilibria in solutions (T = 25 +/- 0.1 degreesC, mu = 0.1 M KNO3). Dimer H2L2 was found to predominate in solution at c(HL) = 0.01 mol/l. Three protonated dimeric (H3L2+, H4L22+, and H5L23+), diprotonated monomeric (H-3(2+)), and triprotonated tetrameric forms (H7L43+)were detected in the system, depending on pH. At lower ligand concentrations (c(HL) = 0.0015 mol/l), the solution contains both dimers and monomers of this compound. The higher dentate number of HL compared to 2-alkylaminomethylphenols allows it to form more number of both mono-and binuclear complexes ([Cu(HL)](2+), [Cu(HL)(2)](2+), [CuL2], [CuL2OH](-), [Cu-2(HL)(2)](4+), and [Cu-2(HL)(2)L-2](2+)), making them more stable.