Mechanistic Study of β-Methyl and β-Hydrogen Elimination in the Zirconocene Compounds Cp‘<sub>2</sub>ZrR(μ-CH<sub>3</sub>)B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> (Cp‘ = Cp, Cp*; R = CH<sub>2</sub>CMe<sub>3</sub>, CH<sub>2</sub>CHMe<sub>2</sub>)
Bibliographic record
Abstract
A kinetics study of β-methyl elimination reactions of the compounds Cp 2 ZrNp(μ-Me)B(C 6 F 5 ) 3 (in various solvents) and Cp* 2 ZrNp(μ-Me)B(C 6 F 5 ) 3 (in CD 2 Cl 2 ) shows that the reactions are accelerated by polar solvents and by steric crowding in the Cp* system, results consistent with previous findings and conclusions that the methyl migrations are accompanied in a concerted process by borate anion departure from the inner coordination sphere of the metal ion. Surprisingly, however, the isobutyl compound Cp* 2 Zr( i -Bu)(μ-Me)B(C 6 F 5 ) 3, which is expected to undergo β-methyl elimination by analogy with an extensive literature on chain transfer processes during propylene polymerization, undergoes very rapid β-hydrogen elimination only.
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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".