Synthesis, characterisation, reactivity, and X-ray structure of cis-carbonylchlorobis[1-methyl-3-(pyridin-2-yl)-1,2,4-triazole-N4N′]ruthenium hexafluorophosphate

Abstract

The compound [Ru(L–L′)₂(CO)Cl]PF₆[L–L′= 1-methyl-3-(pyridin-2-yl)-1,2,4-triazole] has been obtained in high yield from ruthenium trichloride and the pyridyltriazole ligand in dimethylformamide, as a mixture of co-ordination isomers. One of these isomers was obtained using crystallisation techniques and crystallises in the monoclinic space group P2₁/n with unit-cell parameters a= 11.085(1), b= 13.120(2), c= 16.108(2)Å, β= 97.17(1)°, and Z= 4. The metal cation has a cis geometry for CO and Cl, and the triazole ring is bound to the ruthenium centre via its N⁴ nitrogen atom. The CO and Cl groups are trans to the triazole rings of the pyridyltriazole ligand. The average ruthenium nitrogen distance is 2.09 Å. From this compound the species [Ru(L–L′)(CO)L]⁺ have been obtained, where L = NCS^– or H^–. All the compounds have been characterised by spectroscopic, electrochemical, and high-performance liquid chromatographic methods. The results, and in particular the high yield in which the title compound is obtained, strongly suggest that the pyridyltriazole ligand is a weaker π acceptor than 2,2′-bipyridyl.