New
1,2-azolylamidino complexes
cis
-[Ru(bipy)
2
(NH=C(R)az*-κ
2
N
,
N
)](OTf)
2
(R = Me, Ph; az* = pz, indz, dmpz)
are synthesized via chloride abstraction after a subsequent base-catalyzed
coupling of a nitrile with the previously coordinated 1,2-azole. The
synthetic procedure allows the easy obtainment of complexes having
different electronic and steric 1,2-azoylamidino ligands. All of the
compounds have been characterized by
1
H,
13
C,
and
15
N NMR and IR spectroscopy and by monocrystal X-ray
diffraction. Photophysical studies support their phosphorescence,
whereas their electrochemistry reveals reversible Ru
II
/Ru
III
oxidations between +1.13 and +1.25 V (vs SCE). The complexes
have been successfully used as catalysts in the photooxidation of
different thioethers, the complex
cis
-[Ru(bipy)
2
(NH=C(Me)dmpz-κ
2
N
,
N
)]
2+
showing better catalytic performance
in comparison to that of [Ru(bipy)
3
]
2+
. Moreover,
the significant catalytic performance of the dimethylpyrazolylamidino
complex is applied to the preparation of the drug modafinil, which
is obtained using ambient oxygen as an oxidant. Finally, mechanistic
assays suggest that the oxidation reaction follows a photoredox route
via oxygen radical anion formation.