One-electron oxidation of the formally Ru(0) complexes [mesN3]Ru(L)2 ([mesN3] = ((mesityl)N=CMe)2C5H3N; L = C2H4, CO, PMe3) with ferrocenium salts generates paramagnetic cationic complexes which can be isolated in moderate to good yields. Although formally examples of ruthenium in the rare Ru(I) oxidation state, participation of the Ru(II) / [N3]-radical anion formalism must be considered given the well-established redox non-innocence of the [N3] pincer ligand.Odd-electron complexes can also be generated by the comproportionation of formally Ru(0) and Ru(II) complexes. For example, reaction of [N3]RuCl2(L) with half an equivalent of {[N3]Ru(N2)}2(m-N2) in THF rapidly generates equal amounts of the formally Ru(I) species [N3]RuCl(L) and [N3]RuCl(THF). In the case of L = PMe3 and THF these species are highly reactive and undergo rapid hydrogen atom abstraction from solvent to produce the corresponding hydride complexes [N3]Ru(H)(Cl)(L). Formation of the new metal-hydride bond clearly indicates substantial metal-centered reactivity, despite electron delocalization onto the redox-active ligand. In contrast, [N3]RuCl(CO) is less reactive and persists in solution, allowing characterization by spectroscopic methods.The magnetic, electrochemical, spectroscopic and structural properties of the new complexes, along with the results of DFT calculations, will be presented. Preliminary studies of the reactivity with small molecules will also be described.

Odd-electron ruthenium complexes of redox-active bis(imino)pyridine ligands

248th National Meeting (2014)

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