The phosphodiester groups of d(TpT)(-) and d(TpG)(-) coordinate to platinum(II) in N,N-dimethylformamide

The propensity of the phosphodiester group to bind platinum(II) was investigated by examining the reactions of the dinucleotide salts NH4{d(TpT)} and NH4{d(TpG)} with the complexes [Pt(NO3)(NH3)(3)]NO3 (1) and cis-[Pt(NO3)(2)-(NH3)(2)] (2) in N,N-dimethylformamide. d(TpT)(-) coordinates to the platinum atom of both 1 and 2 through either of the two nonbridging phosphoryl oxygen atoms, as revealed by P-31 NMR spectroscopy. Conversely, d(TpG)(-) binds to 1 through the guanine N7 atom. With 2, d(TpG)(-) forms monodentate adducts bound to N7(G), as well as two distinct macrochelates, in which N7(G) and one of the nonbridging phosphoryl oxygens are crosslinked by platinum, We suggest that guanine-phosphoryl macrochelate complexes play a role as intermediates in rearrangements of platinum monoadducts formed with DNA.