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

The dimeric η(6)-hexamethylbenzene ruthenium(II) triazole compounds of formulation [{(η(6)-C(6)Me(6))Ru(N(3)C(2)(CO(2)R)(2))}(2)(μC(2)O(4))] have been synthesized by 1,3-diploar cycloadditions of coordinated azido compound [{(η(6)-C(6)Me(6))Ru(L(1))N(3)}] (1) with substituted acetylene, RO(2)CC(2)CO(2)R via unexpected oxidation of the coordinated ligand to oxalate (where; L(1) = 5-hydroxy-2-(hydroxymethyl)-4-pyrone; R = Me, 3 or Et, 4). In contrast, a similar 1,3-dipolar cycloaddition reaction of [{(η(6)-C(6)Me(6))Ru(L(2))N(3)}] (2) (where; L(2) = tropolone) with acetylene yielded the monomeric triazole compound [(η(6)-C(6)Me(6))Ru(L(2)){N(3)C(2)(CO(2)R)(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.