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.