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