Kinetic Salt Effects and the Specific Influence of Ions on Rate Constants

Pethybridge, Alan D.; Prue, J. E.

doi:10.1002/9780470166185.ch6

Cited by 34 publications

(12 citation statements)

References 163 publications

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“…The latter can give excellent fits up to large ionic strength values but are generally not used by most kineticists. One convenient option is to use the Debye–Hückel equation, also referred to as the Davies equation: , …”

Section: Activation Of Dioxygenmentioning

confidence: 99%

Dioxygen in Polyoxometalate Mediated Reactions

2017

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In this review article, we consider the use of molecular oxygen in reactions mediated by polyoxometalates. Polyoxometalates are anionic metal oxide clusters of a variety of structures that are soluble in liquid phases and therefore amenable to homogeneous catalytic transformations. Often, they are active for electron transfer oxidations of a myriad of substrates and upon reduction can be reoxidized by molecular oxygen. For example, the phosphovanadomolybdate, HPVMoO, can oxidize Pd(0) thereby enabling aerobic reactions catalyzed by Pd and HPVMoO. In a similar vein, polyoxometalates can stabilize metal nanoparticles, leading to additional transformations. Furthermore, electron transfer oxidation of other substrates such as halides and sulfur-containing compounds is possible. More uniquely, HPVMoO and its analogues can mediate electron transfer-oxygen transfer reactions where oxygen atoms are transferred from the polyoxometalate to the substrate. This unique property has enabled correspondingly unique transformations involving carbon-carbon, carbon-hydrogen, and carbon-metal bond activation. The pathway for the reoxidation of vanadomolybdates with O appears to be an inner-sphere reaction, but the oxidation of one-electron reduced polyoxotungstates has been shown through intensive research to be an outer-sphere reaction. Beyond electron transfer and electron transfer-oxygen transfer aerobic transformations, there a few examples of apparent dioxygenase activity where both oxygen atoms are donated to a substrate.

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Section: Activation Of Dioxygenmentioning

confidence: 99%

Dioxygen in Polyoxometalate Mediated Reactions

2017

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“…It should be noted that the magnitude of the rate constant values collected at −78 °C for MnN(Sal t Bu ) and MnN(Sal CF 3 ) by the electrochemical method differ from previous measurements determined by decay of the ligand-to-metal charge-transfer (LMCT) bands in the UV–vis–near-IR (NIR) spectra at the same temperature . This difference observed in the electrochemically determined rate data can likely be attributed to the positive influence of an electrolyte on the rate constant of the bimolecular process involving like-charged species. − …”

Section: Resultsmentioning

confidence: 92%

Elaboration on the Electronics of Salen Manganese Nitrides: Investigations into Alkoxy-Substituted Ligand Scaffolds

2021

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The ligand electronics of salen manganese nitride complexes directly influence the locus of oxidation and, thus, the reactivity of the resulting oxidized species. This work investigates the influence of tert-butoxy, isopropoxy, and methoxy substituents on the electronics of salen manganese nitride species and includes the first documentation of the para Hammett value for the tert-butoxy substituent (σpara = −0.13 ± 0.03). Each alkoxy-substituted complex undergoes metal-based oxidation to form manganese(VI), and the kinetics of bimolecular homocoupling to form N2 were assessed by cyclic voltammetry. Bis-oxidation of the manganese complexes was investigated at low temperature using cyclic voltammery and UV–vis–near-IR spectroscopy, and in combination with theoretical calculations, plausible electronic structures of the dications are provided.

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“…The b factor is an effective interaction coefficient that is determined empirically and typically ranges from À1 b 1. 9 Adam determined the b factor to be À0.146 for his experiments on ultrapure and commercial sodium hypochlorite at ionic strength greater than …”

Section: Resultsmentioning

confidence: 99%

“…8 log k ¼ 1:02m 1=2 1 þ m 1=2 À 1:02bm þ log k 0 (9) In this work, the ionic strength is utilized in units of molarity as opposed to molality as is generally applied. The b factor is an effective interaction coefficient that is determined empirically and typically ranges from À1 b 1.…”

Section: Resultsmentioning

confidence: 99%