Stability constants of the ternary palladium(II) complexes of triamines (diethylenetriamine(dien) and 2,2':6',2-terpyridine(terpy)) and nucleobases (1-methylcytosine(MeC), 9-methyladenine(MeA), 1-methyluracil(MeUH), 1- methylthymine(MeTH), 9-ethylguanine(EtGH), uridine, inosine) or derivatives of amino acids (N-acetylhistamine(Ac-Hm), N-acetylhistidine(Ac-His) and N- acityllysine (Ac-Lys)) were determined by pH-metric titrations. Binding sites of the ligands in the ternary complexes were elucidated by 1H-nuclear magnetic resonance spectroscopy. It was found that all ligands form stable adducts with [Pd(terpy)]2+ and [Pd(dien)]2+, except the [Pd(terpy)Cl]+ / Ac-Lys system, where the formation of the mixed hydroxo complex [Pd(terpy)(OH)]+ predominates. The formation of dinuclear complexes of [Pd(terpy)]2+ and [Pd(dien)]2+ was identified with Ac-Hm and Ac-His (imidazole-N3 / N1) and inosine and EtGH (purine-N1 / N7). The [(Pd(terpy))2LH-1]3+ dinuclear species were detected in slightly acidic media in the ternary systems containing MeC or MeA, in which one of the [Pd(terpy)]2+ units is bonded to N3 of MeC or N1 of MeA, while the second palladium(II) is coordinated by the deprotomated exocyclic amino groups of the ligands.
ASJC Scopus subject areas
- Inorganic Chemistry