Synthesis and characterization of Pd(II) and Pt(II) complexes with triazolopyrimidine derivatives: The crystal structure of [Pd2L2Cl4] where L = 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine

The Pd(II) and Pt(II) complexes with triazolopyrimidine C-nucleosides L1 (5,7-dimethyl-3-(2′,3′,5′-tri-O-benzoyl-β-d-ribofuranosyl-s-triazolo)[4,3-a]pyrimidine), L2 (5,7-dimethyl-3-β-d-ribofuranosyl-s-triazolo[4,3-a]pyrimidine) and L3 (5,7-dimethyl[1,5-a]-s-triazolopyrimidine), [Pd(en)(L1)](NO3)2, [Pd(bpy)(L1)](NO3)2, cis-Pd(L3)2Cl2, [Pd2(L3)2Cl4] · H2O, cis-Pd(L2)2Cl2 and [Pt3(L1)2Cl6] were synthesized and characterized by elemental analysis and NMR spectroscopy. The structure of the [Pd2(L3)2Cl4] · H2O complex was established by X-ray crystallography. The two L3 ligands are found in a head to tail orientation, with a Pd⋯Pd distance of 3.1254(17) Å. L1 coordinates to Pd(II) through N8 and N1 forming polymeric structures. L2 coordinates to Pd(II) through N8 in acidic solutions (0.1 M HCl) forming complexes of cis-geometry. The Pd(II) coordination to L2 does not affect the sugar conformation probably due to the high stability of the C–C glycoside bond.