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.