Scheme 1.

Schematic structure of the square-planar platinum(II) complexes with four N-donors considered in this work: [Pt^II(dien)(N7-Guo)]²⁺ (1), [Pt^II(dien)(N7-dGuo)]²⁺ (2), and [Pt^II(dien)(N7-dGTP)] (3) (dien = diethylenetriamine; Guo = guanosine; dGuo = 2′-deoxy-guanosine; dGTP = 5′-(2′-deoxy)-guanosine-triphosphate). Standard atomic numbering is reported, atoms other than C and H are reported with their standard color code. For simplicity, the platinum oxidation state and bonded N7 have not been indicated in most of the formulae reported in this work for complexes 1–3.