Azidotetrakis(diarylformamidinate)diruthenium(II,III) Compounds: Synthesis, Molecular Structures and Voltammetric Properties; Linear Free Energy Relationships in Dinuclear Compounds VII*,†

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

A series of RuII complexes stabilized with the pentapyridyl ligand Py5Me2 (Py5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine) and with an axial X ligand (X = Cl-, H2O, N3-, 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 [(Py5Me2)RuN3]+ 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 Ru2 metal-metal bonded complexes, which have been reported to undergo irreversible chloride dissociation upon reduction.

Chloro and azido diruthenium complexes bearing electron-rich N,N',N''-triphenylguanidinate ligands

The reaction of Ru(2)(OAc)(4)Cl with N,N',N''-triphenylguanidine (HTPG) produces one of two different compounds depending on the reaction conditions. In acetone in the presence of triethyl amine, the reaction produces tri-substituted Ru(2)(TPG)(3)(OAc)Cl, and in refluxing xylene, the tetra-substituted Ru(2)(TPG)(4)Cl is produced. Both of these new complexes can be cleanly converted into their corresponding azido analogues by reaction with sodium azide in methanol. The X-ray crystal structures of Ru(2)(TPG)(3)(OAc)Cl, Ru(2)(TPG)(3)(OAc)N(3), and Ru(2)(TPG)(4)Cl are presented, along with magnetic, electrochemical, and spectral measurements for each compound. Studies in solution show that, in contrast to Ru(2)(TPG)(3)(OAc)Cl, Ru(2)(TPG)(4)Cl is sterically hindered at the axial positions, and readily dissociates a chloride ion at high ionic strength. Equilibrium constants for chloride association and dissociation have been estimated. Mass spectrometric data suggest that the two azido complexes are precursors to new diruthenium nitrido species.