The stability of the palladium(II) complexes with ethylenediamine, diethylenetriamine and tris(β-aminoethyl)-amine

Complex formation of Pd2+ with ethylenediamine, diethylenetriamine, and tris(β-aminoethyl)amine was investigated at 25 °C and ionic strength 1 using pH and UV-measurements. Bromide and hydroxyl ions were used as auxiliary ligands. Pd2+ forms the strongest complexes of the divalent cations hitherto investigated. In the case of the latter amine, because of its structure a coordination number of four is obtained forming a dimeric complex. The coordination number of the metal ion never exceeds four. The following values of log(Kn/M-1) were obtained: 23.6 ± 0.1 (n = 1) and 18.6 ± 0.1 (n = 2) for the first, and 32.6 ± 0.2 (n = 1) and 7.8 b 0.1 (n = 2) for the second ligand. For the last ligand: log(([Pd2L2]/ ([Pd]2 [L]2))/M-3) = 77.4 ± 0.3.