4 research outputs found
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Mechanistic Insight into Peroxydisulfate Reactivity: Oxidation of the cis,cis-[Ru(bpy)₂(OH₂)]₂O⁴⁺ "Blue Dimer"
One-electron oxidation of the μ-oxo dimer
(cis,cis-[Ruᴵᴵᴵ(bpy)₂(OH₂)]₂O⁴⁺, {3,3}) to {3,4} by S₂O₈²⁻ 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 ratedetermining
step in these reactions is a strongly nonadiabatic
dissociative electron transfer within a precursor ion pair
leading to the {3,4}|SO₄²⁻|SO₄•− ion triple. As deduced from the SO₄•− scavenging experiments with 2-propanol, the SO₄•−
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 ∼25% 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} → 2{3,4} comproportionation, for which kcₒₘ ∼5 × 10⁷ 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•− indicates that its fate must be
quantitatively determined when using S₂O₈²⁻ as an oxidant
Recommended from our members
RoemelingMargoBiochemBiophysicsMechanisticInsightPeroxydisulfate.pdf
One-electron oxidation of the μ-oxo dimer
(cis,cis-[Ruᴵᴵᴵ(bpy)₂(OH₂)]₂O⁴⁺, {3,3}) to {3,4} by S₂O₈²⁻ 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 ratedetermining
step in these reactions is a strongly nonadiabatic
dissociative electron transfer within a precursor ion pair
leading to the {3,4}|SO₄²⁻|SO₄•− ion triple. As deduced from the SO₄•− scavenging experiments with 2-propanol, the SO₄•−
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 ∼25% 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} → 2{3,4} comproportionation, for which kcₒₘ ∼5 × 10⁷ 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•− indicates that its fate must be
quantitatively determined when using S₂O₈²⁻ as an oxidant
Recommended from our members
RoemelingMargoBiochemBiophysicsMechanisticInsightPeroxydisulfateSupportingInfo.pdf
One-electron oxidation of the μ-oxo dimer
(cis,cis-[Ruᴵᴵᴵ(bpy)₂(OH₂)]₂O⁴⁺, {3,3}) to {3,4} by S₂O₈²⁻ 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 ratedetermining
step in these reactions is a strongly nonadiabatic
dissociative electron transfer within a precursor ion pair
leading to the {3,4}|SO₄²⁻|SO₄•− ion triple. As deduced from the SO₄•− scavenging experiments with 2-propanol, the SO₄•−
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 ∼25% 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} → 2{3,4} comproportionation, for which kcₒₘ ∼5 × 10⁷ 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•− indicates that its fate must be
quantitatively determined when using S₂O₈²⁻ as an oxidant
Mechanistic Insight into Peroxydisulfate Reactivity: Oxidation of the <i>cis</i>,<i>cis</i>-[Ru(bpy)<sub>2</sub>(OH<sub>2</sub>)]<sub>2</sub>O<sup>4+</sup> “Blue Dimer”
One-electron
oxidation of the μ-oxo dimer (<i>cis</i>,<i>cis</i>-[Ru<sup>III</sup>(bpy)<sub>2</sub>(OH<sub>2</sub>)]<sub>2</sub>O<sup>4+</sup>, <b>{3,3}</b>) to <b>{3,4}</b> by S<sub>2</sub>O<sub>8</sub><sup>2–</sup> can be described
by three concurrent reaction pathways corresponding to the three protic
forms of <b>{3,3}</b>. 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 <b>{3,4}</b>|SO<sub>4</sub><sup>2–</sup>|SO<sub>4</sub><sup>•–</sup> ion triple. As deduced
from the SO<sub>4</sub><sup>•–</sup> scavenging experiments
with 2-propanol, the SO<sub>4</sub><sup>•–</sup> radical
then either oxidizes <b>{3,4}</b> to <b>{4,4}</b> within
the ion triple, effecting a net two-electron oxidation of <b>{3,3}</b>, or escapes in solution with ∼25% probability to react with
additional <b>{3,3}</b> and <b>{3,4}</b>, that is, effecting
sequential one-electron oxidations. The reaction model presented also
invokes rapid <b>{3,3}</b> + <b>{4,4}</b> → 2<b>{3,4}</b> comproportionation, for which <i>k</i><sub>com</sub> ∼5 × 10<sup>7</sup> M<sup>–1</sup> s<sup>–1</sup> was independently measured. The model provides an
explanation for the observation that, despite favorable energetics,
no oxidation beyond the <b>{3,4}</b> state was detected. The
indiscriminate nature of oxidation by SO<sub>4</sub><sup>•–</sup> indicates that its fate must be quantitatively determined when using
S<sub>2</sub>O<sub>8</sub><sup>2–</sup> as an oxidant