A compound of composition [Pt3(NH3)8(9-MeA)2](NO3)6.2H2O, where 9-MeA = 9-methyladenine, C6H7N5, is reported which contains two (NH3)3Pt(II) residues bound to 9-MeA via N7 and a cis-(NH3)2Pt(II) entity bound to 9-MeA through N1. The two adenine rings are oriented head-to-head in the solid state, while in solution, an equilibrium between two rotamers (head-head, head-tail) exists. The X-ray structure is described, and based on it, the formation of related macrocyclic rings is proposed.