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

Abstract

The Pd(II) and Pt(II) complexes with triazolopyrimidine C-nucleosides L 1 (5,7-dimethyl-3-(2′,3′,5′-tri- O-benzoyl-β- d-ribofuranosyl-s-triazolo)[4,3-a]pyrimidine), L 2 (5,7-dimethyl-3-β- d-ribofuranosyl-s-triazolo[4,3-a]pyrimidine) and L 3 (5,7-dimethyl[1,5-a]-s-triazolopyrimidine), [Pd(en)(L 1)](NO 3) 2, [Pd(bpy)(L 1)](NO 3) 2, cis-Pd(L 3) 2Cl 2, [Pd 2(L 3) 2Cl 4] · H 2O, cis-Pd(L 2) 2Cl 2 and [Pt 3(L 1) 2Cl 6] were synthesized and characterized by elemental analysis and NMR spectroscopy. The structure of the [Pd 2(L 3) 2Cl 4] · H 2O complex was established by X-ray crystallography. The two L 3 ligands are found in a head to tail orientation, with a Pd⋯Pd distance of 3.1254(17) Å. L 1 coordinates to Pd(II) through N8 and N1 forming polymeric structures. L 2 coordinates to Pd(II) through N8 in acidic solutions (0.1 M HCl) forming complexes of cis-geometry. The Pd(II) coordination to L 2 does not affect the sugar conformation probably due to the high stability of the C–C glycoside bond.