The reactions of a mother solution of RuCl
3
with benzimidazole derivatives 2-(2
’
-pyridyl)benzimidazole
(2,2
’
-PyBIm, L
1
) and 2-hydroxymethylbenzimidazole (2-CH
2
OHBIm, L
2
) yielded three novel ruthenium
complexes: (H
2
L
1
)
2
[Ru
III
Cl
4
(CH
3
CN)
2
]
2
[Ru
IV
Cl
4
(CH
3
CN)
2
]·2Cl·6H
2
O(
1
),
mer
-[Ru
III
Cl
3
L
1
(CH
3
CN)]·L
1
·3H
2
O(
2
),
and (HL
2
)
4
[Ru
IV
Cl
6
]·2Cl·4H
2
O(
3
). The isolated compounds were characterised by elemental analyses,
UV-Vis and IR spectroscopy, and magnetic measurements. The nature of the ligands bound to the metal
ions of these compounds and the experimental conditions signi
fi
cantly in
fl
uenced the ruthenium com-
plexes in di
ff
erent oxidation states. The N,N-donor ligand bound to the metal centre is a recognised
stabiliser of the +III state of ruthenium, whereas the lack of ligand coordination promotes the formation
of a mixed (Ru
III
/Ru
IV
) complex. In the case of complex
3
, the absence of a N,O-donor ligand in the co-
ordinate sphere facilitates the formation of the compound in a higher oxidation state. X-ray single crystal
analyses revealed an octahedral geometry in each of the complexes. The crystal structure of ruthenium
complexes is formed by a network of intermolecular classical and unconventional (C
–
H
⋯
π
) hydrogen
bonds. The most interesting feature of the supramolecular architecture of complexes is the existence of a
very rare Cl
−
⋯
π
interaction and
π
⋯
π
stacking, which also contribute to structural stabilisation. Ruthenium
compounds
2
and
3
behave as paramagnets with an octahedral geometry, corresponding to the pres-
ence of one or two unpaired electrons, respectively. The cyclic voltammetric data of complex
2
show
three one-electron redox processes. The
fi
rst redox couple is reversible, whereas the two other couples
have a quasi-reversible nature. In the case of complex
3
, two redox couples are reversible and the elec-
trode processes are connected with exchange of one electron.