Equilibria in aqueous solution between beryllium(II) and d,l-aspartic acid and d,l-methionine

The complex species formed in aqueous solution between beryllium(II) and d,l-aspartic acid (ASP) and d,l-methionine (MET) were studied at 25°C and 0.5 M ionic strength in NaClO4. The application of the least-squares computer program LETAGROP to the experimental potentiometric data, taking into account hydrolysis of the beryllium(II) ion, upon varying the ligand-metal ratios 4:1, 1:1 and 1:2, at beryllium(II) concentrations of 1, 3 and 6 mM, indicates that only the dihydroxide complexes ([Be(OH)2L′]2− for ASP, H2L′ ligand; [Be(OH)2L]− for MET, HL ligand) are formed in significant amounts. The complex species begins to form at pH > 5.5. The formation constants βpqr, were determined.