Synthesis and Characterization of Platinum(II) Complexes with a Diazenecarboxamide-Appended Picolyl-Triazole Ligand

The coordination of the diazenecarboxamides, which were functionalized with the 1-(2-picolyl)-1H-1,2,3-triazole moiety 1, to platinum(II) were studied, where K-2[PtCl4] and cis-[PtCl2(DMSO)(2)] were used as the platinum sources. The picolyl-triazole (pictri) binding unit enabled chelation to the metal centre through the 1,2,3-triazole N-2 and the pyridyl nitrogen atoms under mild reaction conditions. When cis-[PtCl2(DMSO)(2)] was used, with CH2Cl2 or CH3CN as the reaction solvents, the pure, stable diamminedichloridoplatinum(II) complexes 2 were isolated by filtration in 39 to 83% yield. The products were structurally characterized in solution by H-1, C-13 and Pt-195 NMR spectroscopy. The Pt-195 NMR chemical shifts for 2 appear in the region of -2203 to -2207 ppm. The structure of complex 2a was confirmed by single-crystal X-ray crystallography. The formation of the platinum complexes 2 was monitored using NMR spectroscopy. The complexation with cis-[PtCl2(DMSO)(2)] in [D-7]dmf proceeded through several intermediates, as indicated by the 195Pt NMR spectra with resonances in the range of -3055 to -2907 ppm. Similarly, the reaction of cis-[PtCl2(DMSO)(2)] with diazenecarboxamide, which was functionalized with the nonchelating 1-(2-aminoethyl)-1,2,3-triazole derivative, was examined by NMR spectroscopy.