Coordination Centres of Purine Nucleotides: Adenosine‐5′‐diphosphate and Adenosine‐5′‐triphosphate in their Reactions with Nickel(II), Cobalt(II) and Tetramines

Abstract

AbstractInteractions between the nucleotides: adenosine‐5′‐diphosphate (ADP) and adenosine‐5′‐triphosphate (ATP) with NiII and CoII ions, as well as with spermine (Spm) and 1,11‐diamine‐4,8‐diazaundecane (3,3,3‐tet) are the subject of this study. Composition and stability constants of mixed complexes thus formed have been determined on the basis of the potentiometric measurements, whereas interaction centres in ligands have been identified by VIS and NMR spectral parameter analysis. Mixed tetraprotonated complexes with NiII, i.e. Ni(ADP)H4(Spm), Ni(ATP)H4(Spm), Ni(ADP)H4(3,3,3‐tet) and Ni(ATP)H4(333‐tet), are identified as ML·······L′ type adducts, in which the main coordination centre is the nucleotide nitrogen N(1) or N(7) donor atom, and the fully protonated polyamine is engaged in noncovalent interactions with nucleotide phosphate group oxygen atoms. Ni(ADP)H2(Spm), Ni(ATP)H2(Spm), Ni(ADP)H2(3,3,3‐tet) and Ni(ATP)H2(3,3,3‐tet) complexes represent the {N3} coordination type In diprotonated mixed complexes of NiII with spermine are weak noncovalent interligand interactions, providing an additional stabilising effect. Formation of ML·······L′ type molecular complexes has been observed in systems with CoII: Co(ADP)H4(Spm), Co(ATP)H4(Spm), Co(ADP)H4(3,3,3‐tet) and Co(ATP)H4(3,3,3‐tet), in which the N(7) atom and oxygen atoms of the phosphate group are involved in coordination and the fully protonated polyamine is engaged in noncovalent interactions with the nucleotide N(1).