Palladium(II) Complexes Containing Mixed Nitrogen-Sulphur Donor Ligands: Interaction of [Pd(Methionine Methyl Ester)(H2O)2]2+ with Biorelevant Ligands
Table 1
Formation constants for complexes of [Pd(MME)(H2O)2]2+ with amino acids at 25°C and 0.1 M ionic strength.
System
M
L
Ha
Pd(MME)-OH
1
0
−1
−5.29 (0.01)
5.29
1
0
−2
−12.96 (0.05)
7.67
2
0
−1
−2.46 (0.07)
Glycine
0
1
1
9.60 (0.01)
9.60
0
1
2
11.93 (0.02)
2.33
1
1
0
10.40 (0.03)
Alanine
0
1
1
9.69 (0.01)
9.69
0
1
2
11.89 (0.02)
2.20
1
1
0
10.33 (0.05)
Proline
0
1
1
10.52 (0.01)
10.52
0
1
2
12.03 (0.04)
1.51
1
1
0
10.79 (0.02)
-Phenyl alanine
0
1
1
9.12 (0.01)
9.12
0
1
2
11.01 (0.02)
1.89
1
1
0
9.87 (0.04)
Imidazole
0
1
1
7.04 (0.01)
7.04
1
1
0
8.41 (0.04)
1
2
0
15.93 (0.06)
Lysine
0
1
1
10.51 (0.00)
10.51
0
1
2
19.71 (0.01)
9.20
1
1
0
11.15 (0.01)
10.17
1
1
1
20.29 (0.07)
9.14
Methionine
0
1
1
8.76 (0.00)
8.76
1
1
0
9.05 (0.04)
Histamine
0
1
1
9.88 (0.01)
9.88
0
1
2
15.30 (0.01)
5.42
1
1
0
12.54 (0.04)
3.43
1
1
1
15.97 (0.1)
3.43
Histidine
0
1
1
9.52 (0.01)
9.52
0
1
2
15.81 (0.02)
6.29
1
1
0
14.26 (0.07)
1
1
1
18.30 (0.09)
4.0
aM, L, and H are the stoichiometric coefficients corresponding to Pd(MME), amino acid, and H+, respectively; the coefficient −1 refers to a proton loss; b of Pd(MME)-amino acids complexes, standard deviations are given in parentheses; sum of square of residuals is less than ; cthe p of the ligands and the protonated complexes.
