Complexes of beryllium(II) with N-(2-Acetoamido) iminodiacetate and ligands containing a phosphonate group

Complexes formed by beryllium(II) with N-(2-Acetoamido)iminodiacetic Acid (ADA, H2L), Aminomethylphosphonic Acid (AMPA, H2L), and (Phosphonomethyl)iminodiacetic Acid (MPDA, H4L) were investigated in aqueous solution using potentiometric measurements. The protonation constants of the three ligands were determined at 298 K at ionic strength 0.5 M made up with [(CH3)4N]Cl. Five complexes of ADA-Be(II) were found: BeL, [BeL2]2-, Be(HL)2, [Be2(OH)(HL)]2+ and Be3(OH)3(HL)3. For the AMPA-Be(II) system we found eight species, the aforementioned, and also [BeHL]+, [Be(OH)2L]2- and [Be2(OH)(HL)2]+. For the MPDA-Be(II) system we found six species: [BeHL]-, Be2(OH)(HL), [Be2(OH)(H2L)]+, [Be2(OH)(HL)2]3-, [Be3(OH)3(HL)3]6- and Be3(OH)3(H2L)3. The corresponding formation constants were determined at 25C at ionic strength 0.5 M in [(CH3)4N]Cl. Theoretical calculations using density functional theory on the experimental species found in solution were carried out.