Synthesis, Characterization, and Electrochemistry of Diruthenium(III,II) and Monoruthenium(III) Complexes Containing Pyridyl-Substituted 2-Anilinopyridinate Ligands

Reaction of the metal−metal bonded complex Ru2(O2CCH3)4Cl with 2-anilino-4-methylpyridine leads to the (3,1)
isomer of the diruthenium(III,II) complex Ru2(ap-4-Me)4Cl, 1 while the same reaction with 2-anilino-6-methylpyridine
gives the monoruthenium(III) derivative Ru(ap-6-Me)3, 2. Both compounds were examined as to their structural,
electrochemical, and UV−visible properties, and the data were then compared to that previously reported for (4,0)
Ru2(2-Meap)4Cl and other (3,1) isomers of Ru2(L)4Cl with similar anionic bridging ligands. ESR spectroscopy indicates
that the monoruthenium derivative 2 contains low-spin Ru(III), and the presence of a single ruthenium atom is
confirmed by an X-ray structure of the compound. The combined electrochemical and UV−vis spectroelectrochemical
data indicate that the diruthenium complex 1 is easily converted to its Ru24+ and Ru26+ forms upon reduction or
oxidation by one electron while the monoruthenium derivative 2 also undergoes metal-centered redox processes
to give RuII and RuIV complexes under the same solution conditions. The reactivity of 1 with CO and CN- was also
examined.