Bi Is the New B: High Lewis acidity at a planar, trivalent, neutral, electropositive p-block element
Bibliographic record
Abstract
Geometric perturbation away from VSEPR-predicted structures can engender unusual frontier MO situations leading to high Lewis acidity. Recently we reported a T-shaped bismuth triamide, which exhibited planar Lewis acidity that was unprecedented for neutral Group 15 compounds. We now report a comprehensive computational assessment of the origins of planar Lewis acidity in such compounds. We subsequently use several metrics such as MO energies, the Global Electrophilicity Index, ligand coordination strengths, and Fluoride Ion Affinity to show that electronic variation can be combined with the unusual geometry at bismuth to achieve fine tuning of Lewis acid strength. Our calculations reveal for the first time a surprisingly high Lewis acidity – comparable to or exceeding that of polyfluorinated triarylboranes – as well as high rigidity at neutral planar bismuth triamides. These results foreshadow the potentially broad applications of a hitherto unexplored class of compounds – planar bismuthanes – in several contexts such as anion sensing, Lewis acid catalysis, weakly-coordinating anion chemistry and materials science that are currently dominated by Lewis acidic triarylboranes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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 source (direct Gemma or distilled Codex), 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".