Mechanisms of Intramolecular Rearrangements of Cyclic Siloxycarbenes
Bibliographic record
Abstract
Intramolecular rearrangements of 3-sila-2-oxacyclohexylidene have been investigated using hybrid density functional theory calculations, the quantum theory of atoms in molecules, and the electron localization function. Mechanisms for 1,2-H migration, ring contraction, and decarbonylation have been examined. The mechanism for 1,2-H migration was shown to involve a typical hydride-like shift from the migration origin to the “vacant” carbene p orbital, while ring contraction was found to occur via a concerted pathway involving a front-side nucleophilic attack by the carbene lone pair at silicon as opposed to a stepwise pathway involving an acyl−silyl biradical intermediate. Decarbonylation, on the other hand, was shown to be a stepwise reaction that preferentially occurs via the intermediacy of silacyclopentanone rather than acyl−silyl and alkyl−silyl biradicals. Computed energetics and thermodynamics indicate that 1,2-H migration and ring contraction are considerably more favorable than decarbonylation. Finally, AIM analysis reveals that the changes in molecular structure associated with 1,2-H migration involving a hydride-like shift to the “vacant” carbene p orbital occur via a conflict mechanism, whereas those associated with ring contraction (or 1,2-silyl migration) involving front-side nucleophilic attack by the carbene lone pair at silicon occur via a bifurcation mechanism . The latter findings further suggest that AIM analysis may be a viable approach to unambiguously distinguish between reaction mechanisms.
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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 | 0.000 | 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".