Table 1: The Acid Dissociation Constants of 1,10-phenanthroline (Phen) and the Stability Constants of the Sc(III), Y(III) and La(III)-Phen Complexes (25 ± 0.1°C, I = 0.1 M KNO3).

RowEquilibrium ConstantPhenSc(III)Y(III)La(III)

1H2L+2 HL+ + H+log KH2L1.50 ± 0.08 (1.95) [30]
HL+ L + H+log KHL4.92 ± 0.08 (4.77) [30]

2M3+ + L ML+3log β 110.83 ± 0.029.47 ± 0.048.47 ± 0.03
M3+ + 2L ML2+3log β 220.70 ± 0.02