Mono- and dinuclear platinum(II) compounds with 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine. Structure, cytotoxic activity and reaction with 5′-GMP

Mono- and dinuclear platinum(II) coordination compounds of formula cis-[PtCl₂(NH₃)(dmtp)], 1, cis-[PtCl₂(dmtp)₂], 2 and {H⁺[C₂₈H₃₂Cl₂N₁₆Pt₂]²⁺(NO₃)₃(H₂O)₆}, 3, in which dmtp is 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine have been synthesized and characterized by infrared and by ¹H, ¹³C, ¹⁹⁵Pt NMR spectroscopy. The coordination units of the cationic species of formula [Pt₂(μ-dmtp)₂Cl₂(dmtp)₂]²⁺ are built up by two platinum atoms in a square-planar environment. Two sites are occupied by two 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) bridging ligands which are linked to both metal atoms through their nitrogen atoms in positions 3 and 4. The other two positions are occupied by one monodentate 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) molecule and a coordinated chloride. This compound is the first in which the same triazolopyrimidine ligand (dmtp) coordinates to a metal ion in two different ways, i.e. bridging bidentate and non-bridging monodentate. In addition, the interaction of compounds 1 and 2 with 5′-GMP was investigated in solution by ¹H NMR spectroscopy. The cytotoxicity of all the new platinum(II) compounds were studied by using two different cell lines: T47D (breast cancer) and HCV29T (bladder cancer).