Synthesis of a Transient Cationic Phosphaborene and its Trapping by Facile Aliphatic C−H Bond Activation
Bibliographic record
Abstract
Abstract The synthesis of a transient cationic phosphaborene [(Mes*)P=B(CAAC)] + (Mes*=2,4,6,–tri‐ tert ‐butylphenyl, CAAC=cyclic alkylamino carbene) by halide abstraction from the B‐brominated analogue is reported. This species was found to undergo rapid and selective intramolecular aliphatic C−H bond activation to yield a phosphinoborenium cation, which undergoes facile deprotonation to give a cyclic base‐stabilized phosphaborene. Computational investigation of the mechanism of C−H activation indicates a boron‐centred activation route with an exceptionally low barrier of 8 kJ mol −1 , followed by a nearly barrierless hydride migration from boron to phosphorus. This underscores the enhanced reactivity of phosphaborenes compared to their lighter iminoborane analogues and indicates that steric stabilization alone is likely insufficient to isolate persistent cationic phosphaborenes, necessitating the use of alternative design strategies.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".