Mechanistic Insight into Peroxydisulfate Reactivity: Oxidation of the cis,cis-[Ru(bpy)2(OH2)]2O(4+) "Blue Dimer".
J Phys Chem B
; 119(24): 7749-60, 2015 Jun 18.
Article
em En
| MEDLINE
| ID: mdl-25819370
ABSTRACT
One-electron oxidation of the µ-oxo dimer (cis,cis-[Ru(III)(bpy)2(OH2)]2O(4+), {3,3}) to {3,4} by S2O8(2-) can be described by three concurrent reaction pathways corresponding to the three protic forms of {3,3}. Free energy correlations of the rate constants, transient species dynamics determined by pulse radiolysis, and medium and temperature dependencies of the alkaline pathway all suggest that the rate-determining step in these reactions is a strongly nonadiabatic dissociative electron transfer within a precursor ion pair leading to the {3,4}|SO4(2-)|SO4(â¢-) ion triple. As deduced from the SO4(â¢-) scavenging experiments with 2-propanol, the SO4(â¢-) radical then either oxidizes {3,4} to {4,4} within the ion triple, effecting a net two-electron oxidation of {3,3}, or escapes in solution with â¼25% probability to react with additional {3,3} and {3,4}, that is, effecting sequential one-electron oxidations. The reaction model presented also invokes rapid {3,3} + {4,4} â 2{3,4} comproportionation, for which kcom â¼5 × 10(7) M(-1) s(-1) was independently measured. The model provides an explanation for the observation that, despite favorable energetics, no oxidation beyond the {3,4} state was detected. The indiscriminate nature of oxidation by SO4(â¢-) indicates that its fate must be quantitatively determined when using S2O8(2-) as an oxidant.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Rutênio
/
Sulfatos
/
Complexos de Coordenação
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article