Article,

Ancillary ligand determination of the spin location in both oxidised and reduced forms of diruthenium complexes bridged by bis-bidentate 1,4-bis(2-phenolato)-1,4-diazabutadiene

, , , , , , and .
Dalton Transactions, (2007)
DOI: 10.1039/b617468j

Abstract

The rare bridging mode of 1,4-bis(2-hydroxyphenyl)-1,4-diazabutadiene = glyoxalbis(2-hydroxyanil) (L2-) is adopted in (μ-L2-)[RuII(bpy)2]22+ (12+), obtained as bis-perchlorate. Four well accessible redox forms of 1n (n = 4+, 3+, 2+, +) were characterized by UV-visible-NIR spectroelectrochem. The (3+) and (+) intermediates also were studied by EPR, both showing radical-type signals close to g = 2. This observation stands in Stark contrast to EPR results previously obtained for the related (μ-L)[Ru(acac)2]2n, n = + and -, both of which exhibit metal-centered spin. In combination with the UV-visible-NIR spectra these results suggest the preferential involvement of the multistep ligand redox system Ln- in the electron transfer processes. The relative stabilization of RuII by p-accepting bpy is made responsible for the oxidn. of the ligand L2- instead of the metal. [on SciFinder(R)]

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