La liaison metal — metal dans les clusters M12O36: II — Preparation et etude structurale de la phase La3Ru3O11

La₃Ru₃O₁₁ was prepared either by oxidation of mixtures of $\text{3}\text{2}\text{La}{}_2\text{O}{}_3$: 3 Ru with KClO₃ at 900°C or by the oxidation of LaRuO₃ at 920°C with KClO₃, both in a gold boat introduced in a sealed silica tube. The crystal structure of this compound ($\text{a}\text{= 9.466(2)}\text{A}\text{?}\text{, S.G. Pn}\text{3,}\text{Z}\text{=4}$) has been solved by Fourier and least-squares methods to R = 0.022 (R_W = 0.031). As for the previously described Bi₃Ru₃O₁₁ and La₄Ru₆O₁₉, it contains ruthenium in formal oxidation state of 4.33; however, there is no longer metal - metal interaction, owing to the greater Ru - Ru distance (3.00 Å) and the closer approach of bridging oxygen (2.47 Å) within the dimeric unit Ru₂O₁₀. Therefore, this interaction is not a prerequisite for the formation and stability of the three-dimensional network Ru₁₂O₃₆.