Artikel,

2,2'-Azobis(pyridine) (abpy) as a multiply reducible tetradentate ligand. EPR evidence for the configurational dependence of intramolecular electron transfer in the stereoisomeric tris-chelate ruthenium complexes [Ru(abpy)n(bpy)3-n]m (n = 2, 3; m = 2+ to 3-)

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Inorganic Chemistry, 32 (15): 3362--3368 (1993)
DOI: 10.1021/ic00067a029

Zusammenfassung

Fac- and mer-[Ru(abpy)3]2+ (abpy = 2,2'-azobis(pyridine) and 2 out of the 3 possible diastereoisomers of [Ru(abpy)2(bpy)]2+ were isolated via HPLC and identified by their 1H NMR spectra. Electrochem. potentials for several 1-electron redn. steps and UV/visible spectroelectrochem. features vary to a small but detectable degree for the resp. pairs of isomers. The absence of a room-temp. EPR signal for 1 of the 2 isolated isomers of [RuII(abpy-)(abpy)(bpy)].bul.+ demonstrates the structural requirements for intramol. electron transfer. A 99,101Ru EPR hyperfine coupling of $\sim$0.8 mT was established for the previously reported radical ion [Ru(abpy)(bpy)2].bul.+. The free a-azimino chelate is in mononuclear complexes of abpy render these systems suitable for the construction of polynuclear compds. The exceptional p-acceptor capability of abpy is illustrated by the reversible acceptance of $\geq$8 electrons by [(Ru(bpy)2]2(μ,η4-abpy)n. [on SciFinder(R)]

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