Synthesis, characterization and solution behavior of a systematic series of pentapyridyl-supported Ru complexes: comparison to bimetallic analogs.

A series of Ru complexes stabilized with the pentapyridyl ligand PyMe (PyMe = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine) and with an axial X ligand (X = Cl, HO, N, MeCN) were prepared and characterized in the solid state and in non-aqueous solution. The cyclic voltammograms of these complexes in MeCN reflect a reversible substitution of the axial X ligand with MeCN. Irreversible ligand substitution of [(PyMe)RuN] is also observed in propylene carbonate, but only at oxidizing potentials that decompose the azide ligand. The monometallic chloride and azide species are compared with analogous Ru metal-metal bonded complexes, which have been reported to undergo irreversible chloride dissociation upon reduction.