Dynamic hyperconjugation induced bond-angle rotation isomerization mechanism and anionic conformational rigidity-dependent melting points of ionic liquids
Bibliographic record
Abstract
The pyramidal inversion of trisubstituted heteroatoms is well-recognized. However, the stereochemistry of bicoordinated heteroatoms is poorly developed and few examples assumedly isomerize by double-torsion motion or bond-angle inversion. Here, by using ab initio molecular dynamics combined with metadynamics simulation, we reveal an unexpected competing isomerization mechanism, namely dynamic π → σ* negative hyperconjugation induced coupled rotation of bond and bond angle leads to helix inversion in bis(trifluoromethane)sulfonamide (TFSI-), making TFSI- follow four distinct trans-cis isomerization pathways with diverse energy barriers (12–52 kJ mol-1) which are significantly higher than 3.6 kJ mol-1 of sole pathway estimated by conventional static calculations. Our quantitative simulations and experiments results confirm the positive correlation between overall stability of cis-TFSI- with polarity of countercations. The melting points (Tm) of TFSI--based ionic liquids (ILs) linearly rise with the conformational rigidity of TFSI- in the ion pair state, offering a new fundamental perspective on the origin of low Tm of ILs.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".