The tris(picolinate)vanadate(II) ion: Redox properties and electron transfer kinetics with cobalt(III) amines |
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Authors: | Henrique E. Toma Fernando T.P. Lellis |
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Affiliation: | Instituto de Quimica, Universidade de São Paulo, CP 20780, São Paulo, SP, Brazil |
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Abstract: | Vanadium(II) ions form with the pyridine-2-carboxylate ligand a deep blue, tris-substituted complex absorbing at 660 nm (ε = 7.2 × 103 M?1) cm?1) with a shoulder at 450 nm. Reversible spectroelectrochemistry and cyclic voltammetry were observed for this complex, with E = ?0.448 V vs NHE, and ΔSrcθ = ?6 cal · mol?1 · deg?1. Electron transfer kinetics with [CO(en)3]3+ led to k12 = 3100 M?1 s?, ΔH≠ = 12.4 kcal · mol?1 and ΔS≠ = ?0.9 cal · mol?1 · deg?1 (I = 0.10 M). For the related [Co(NH3)6]3+ complex, k13 = 1.9 × 104 M?1 s?1. The self-exchange rate constant and activation parameters were analysed in terms of relative Marcus theory. |
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Keywords: | Author to whom correspondence should be addressed. |
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