Proton NMR study of the interaction of cis ‐dichloro‐diamine‐platinum(II) with poly(I) and poly(I)·poly(C)

The fixation of cis (NH 3 ) 2 Cl 2 Pt(II) to poly(I)·poly(C) leads to the formation of two complexed species. One involves coordination to a single base (accounting for about 70% of the total platinum bound over the r b range 0.07–0.25) and the other to two bases which are not adjacent to each other but may be on the same strand and separated by a loop. Reaction of the platinum compound with poly(I) gives in addition to the above two species a minor one (about 15%, independent of r b over the range 0.05–0.30) in which the platinum is bound to two adjacent bases. The availability of such coordination reduces the dominance of the 1:1 species, which, however, remains the major one (ca. 55%).