Guanosine-5′-monophosphate (5′-GMP) reacts with Pt(II) and Mg(II) metal ions to give complexes of the type Pt(5′-GMP)nCl2•xH2O, cis- and trans-[Pt(NH3)2(5′-GMP)2]Cl2•xH2O and Mg(5'-GMP2)•xH2O, where n = 1, 2, 3, 4 and x = 4–10.Spectroscopic and chemical evidence showed marked similarities with those of the structurally known N7-bonded 5′-GMP complexes of Mn(II), Co(II), Ni(II), Cu(II), and Cd(II) metal ions. Therefore, Pt(II) and Mg(II) are also found to be N7-bonded in these series of nucleotide complexes.The direct phosphate coordination was observed in Mg(II) nucleotide complexes obtained from acidic solution, whereas Mg(II) complexes prepared from neutral solution showed no direct phosphate–Mg(II) interaction. Pt(II) complexes exhibited no direct phosphate metal bonding, while the possibility of an indirect Pt(II)–phosphate interaction through a hydrogen-bonded water molecule can be proposed here.