Platinum(II) coordination to N1 and N7,N1 of guanine: cis-DDP model cross-links in the interior and simultaneous cross-links at the periphery and the interior of DNA

A series of compounds containing p-methylguanine ligands platinated exclusively at N1 or simultaneously at N1 and N7 were prepared and characterized. The starting material for all the complexes was (dien Pt 9-MeGH-N super 7)2+ reacted with a Pt electrophile. It was found that reactions at N7 are completed within minutes as soon as the N1 position is platinated in complexes containing the N1-bound Pt(II). The Pt in (en)Pt(9-MeG-N super 1)2.3H2O has a square-planar coordination geometry and cis-(NH3 2 Pt 1-MeU 9-MeGH-N super 1)1+ reveals a tautomeric structure.