Structural and spectral studies of halogeno complexes of Tri- and Tetra-valent ruthenium

Abstract

A preparative study of chloro and bromo complexes of tri- and tetra-valent ruthenium has shown that the principal ruthenium(III) chloro species, isolated with alkali metal cations from HCl solution, are [RuCl₆]^3- and [RuCl₅H₂O]^2-. But in the case of the ruthenium(III) bromo system the only anionic product isolated was [Ru₂Br₉]^3-. The dinuclear anion was also reversibly oxidized in solution to the ruthenium(IV) species [RuBr₆]^2-. Structural studies, by X-ray powder diffraction, have highlighted the close structural similarity of K₂ [RuBr₆] and K₃ [Ru₂Br₉]. A Ru-Ru bond is proposed for the dinuclear unit. Both X-ray structural and infrared studies have been carried out on the complexes isolated.