Reviews triply halide bridged binuclear ruthenium
systems of the type [L₍₃₋ₓ₎ ClₓRuCl₃ RuClᵧL₍₃₋ᵧ₎] in
oxidation states ranging from Ru₂(II/II) to Ru₂(III/III).
In the present work, organo-soluble salts of [Ru₂X₉]³⁻
(X = CI,Br) are described and their electrochemical,
magnetic and spectroscopic properties investigated.
Electrosynthesis of the oxidised derivatives [Ru₂X₉]²⁻ and
[Ru₂X₉]⁻, and their characterisation by electronic
absorption spectroscopy and magnetic susceptibility
measurements have helped to elucidate their electronic
nature, leading to a greater understanding of the nature
of ruthenium triple halide-bridged complexes in general.
Mixed-valence triple chloro bridged binuclear
complexes of ruthenium bearing NH₃ or H₂0 terminal ligands
such as [Ru₂Cl₃(NH₃)₆]²⁺ and [Ru₂Cl₃(H₂O)₆]²⁺ are
discussed. A comprehensive examination of the redox
properties of [Ru₂Cl₃(NH₃)₆]²⁺ achieved in non-aqueous
media, and of optical spectra in differing oxidation
states, are reported. The underlying metal metal
interactions are discussed in relation to the influence of
terminal ligand basicity.
A sequence of binuclear complexes of the type
[Ru₂ Brₓ(AsR₃) (₉₋ₓ)] (x = 5,6)] have been synthesised and
previous suggestions regarding their structure as
indicated by esr studies and their electrochemical
behaviour, have been enhanced and reinforced.
Electroreduction of mer [OsCl₃ (PMe₂Ph)₃ ] in a variety
of coordinating media has produced a range of 6-coordinate
Os(II) monomeric complexes in two separable isomeric
forms. In non-coordinating solvents the Os(III) complex is
found to expel chloride under most conditions, to give a
detectable 5-coordinate intermediate, which can react
under favourable conditions to produce doubly- and
triply-bridged binuclear species. This series of
electro-initiated reactions has so far yielded many
separate complexes, identified by both spectroscopic
methods and voltammetric data.
Voltammetric measurements establish a reversible
one-electron oxidation for the complex [RuCl₅NO]²⁻. Bulk
electrogeneration of the resulting oxidised species has
allowed i.r, esr and magnetic susceptibility measurements
to confirm its existance as the low-spin [RuCl₅NO]⁻ ion,
in contrast to previous reports.
Electrochemical studies on [Os₂(OCOR)₄Cl₂] (R = Et,
ⁿPr) and [Os₂(hp)₄ CI₂] (hp = hydroxypyridinate anion)
establish a reversible one-electron reduction for these
complexes, producing the first examples of species
containing the Os₂⁵⁺ core. These derivatives have been
characterised by voltammetry, electronic absorption
spectroscopy, esr spectroscopy and magnetic susceptibility