COMPLEX-FORMATION OF PDII ION WITH THE TRIPODAL LIGAND TRIS[2-(DIMETHYLAMINO)ETHYL]AMINE

The complex formation of Pd(II) with tris[2-(dimethylamino)ethyl]amine (N(CH2CH2N(CH3)2)3, Me6tren) was investigated at 25-degrees and ionic strength I = 1, using UV/VIS, potentiometric, and NMR measurements. Chloride, bromide, and thiocyanate were used asauxiliary ligands. The stability constant of [Pd(Me6tren)]2+ in various ionic media was obtained: log beta([Pd(Me6tren)]) = 30.5 (I = 1(NaCl)) and 30.8 (I = I(NaBr)), as well as the formation constants of the mixed complexes [Pd(HMe6tren)X]2, from [Pd(HMe6tren)(H2O)]3+: log K = 3.50 (X- = Cl-) and 3.64 (X- = Br-) and [Pd(Me6tren)X]+ from [Pd(Me6tren)(H2O)]2+: log K = 2.6 (X- = Cl-), 2.8(Br-) and 5.57 (SCN-) at I = 1 (NaClO3). The above data, as well as the NMR measurements do not provide any evidence for the penta-coordination of Pd(II), proposed in some papers.