Activation of an alkyne: the preparation, structure, and reactivity of an acetylenic amidinium ion derived from an <i>N</i>-heterocyclic carbene
Bibliographic record
Abstract
(Bromoethynyl)benzene dissolved in hexane reacts with 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) to produce the acetylenic amidinium salt [Ph-C≡C-IMes][Br]. Treatment of the bromide salt with KPF6 then results in the isolation of solid [Ph-C≡C-IMes][PF6]. Both salts have been characterized spectroscopically and their structures determined using X-ray crystallography. Crystals of a hydrolysis product were also isolated from this reaction on one occasion and its structure is reported. This led us to explore the reactivity of the bromide salt further. It was found to react rapidly with sodium azide (NaN3), azidotrimethylsilane ((CH3)3Si-N3), cyanotrimethylsilane ((CH3)3Si-CN), and also with IMes. All of the addition products have been characterized using X-ray crystallography.
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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) | 0.001 | 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 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".