Mono and dinuclear areneruthenium(ii) triazoles by 1,3-dipolar cycloadditions to a coordinated azide in ruthenium(ii) compounds

Abstract

The dimeric η⁶-hexamethylbenzene ruthenium(II) triazole compounds of formulation [{(η⁶-C₆Me₆)Ru(N₃C₂(CO₂R)₂)}₂(μC₂O₄)] have been synthesized by 1,3-diploar cycloadditions of coordinated azido compound [{(η⁶-C₆Me₆)Ru(L₁)N₃}] (1) with substituted acetylene, RO₂CC₂CO₂Rvia unexpected oxidation of the coordinated ligand to oxalate (where; L₁ = 5-hydroxy-2-(hydroxymethyl)-4-pyrone; R = Me, 3 or Et, 4). In contrast, a similar 1,3-dipolar cycloaddition reaction of [{(η⁶-C₆Me₆)Ru(L₂)N₃}] (2) (where; L₂ = tropolone) with acetylene yielded the monomeric triazole compound [(η⁶-C₆Me₆)Ru(L₂){N₃C₂(CO₂R)₂}] (where; R = Me, 5; Et, 6). The compounds were characterized by spectroscopy and the structures of representative compounds 4 and 6 have been determined by single crystal X-ray diffraction. The two ruthenium centres in the compound 4, are linked by a tetra-dentate oxalate group. Both compounds, 4 and 6, crystallized in a triclinic space group P-1.