Synthesis, spectroscopic and structural characterization of new Ru-II and Ru-III complexes containing triazole- and thiadiazole-type ligands

The chemical behavior of triazole, thiadiazole, and triazoline derivatives of thiocarbonohydrazide towards cis-[RuCl2(DMSO)(4)] (2) was studied. React ion of 4-amino-5-methylthio-3-(2-pyridyl)-1,2,4-triazole (L1) with 2 gave t wo diastereomeric complexes, trans,cis-[RuCl2(DMSO)(2)(L1)] (3) and chiral cis,cis-[RuCl2(DMSO)(2)(L1)] (4). Reaction of 2 with 2-(2-formylhydrazino)- 1,3,4-thiadiazole in MeOH gave the complex trans,cis-[RuCl2(DMSO)(2)(L2)] ( 5) with concomitant deformylation of the starting ligand. The process was c atalyzed by Ru-II in very low yield. Synthesis of the Ru complexes of 4-ami no-3-methyl-1,2,4-Delta(2)-triazoline-5-thione (L3) and 4-amino-3-ethyl-1, 2,4-Delta(2)-triazoline-5-thione (L4) resulted in an interesting oxidation of the metal promoted by DMSO, Reaction of 2 with these ligands in a 6 N HC l solution led to the isolation of the complexes mer-[RuCl3(DMSO)(L3)].1/2 H2O (6) and mer-[RuCl3(DMSO)(L4)].1/2 H2O (7). The complex mer-[RuCl3(DMSO) (L4)].CH3COOH . H2O (7') was obtained by recrystallization of 7 from ethyl acetate. The complexes 6, 7, and 7' were highly stable in HCl solutions an d acetone but not in neutral aqueous solution. To the best of our knowledge this is the first report of Ru-III complexes with an N-N-C-S chelating sys tem.