Pressure effects and solvent dynamics in the electrochemical kinetics of the tris(hexafluoroacetylacetonato)ruthenium(III)/(II) couple in nonaqueous solvents
Bibliographic record
Abstract
Rate constants and reactant diffusion coefficients for the Ru(hfac) 3 0/ electrode reaction have been measured at 25°C as functions of pressure (0-200 MPa) in acetone, acetonitrile, methanol, and propylene carbonate. In sharp contrast to the negative volumes of activation ΔV ex found for the corresponding bimolecular self-exchange reaction in organic solvents, the volumes of activation ΔV el for the electrode reaction are markedly positive, ranging from 8 to 12 cm 3 mol 1 . The volumes of activation ΔV diff for reactant diffusion (which can be equated to the volume of activation ΔV visc for viscous flow) range from 12 to 19 cm 3 mol 1 . For the Debye solvents acetonitrile and acetone at least, ΔV el is given within the experimental uncertainty by ΔV diff + (ΔV ex /2). In this relation, the numerical value of ΔV diff represents indirectly the dominant contribution of solvent dynamics (solvent friction) to ΔV el , and ΔV ex /2 represents the pressure dependence of the free-energy barrier height for the electrode reaction. It is proposed that solvent friction is important in nonaqueous electrode processes but not in the corresponding bimolecular self-exchange reactions because the free-energy activation barrier is twice as high in the latter.Key words: electrode reaction kinetics, solvent dynamics, electron transfer mechanisms, pressure effects, volume of activation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".