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 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 | 0.011 | 0.004 |
| Meta-epidemiology (narrow) | 0.012 | 0.013 |
| Meta-epidemiology (broad) | 0.013 | 0.006 |
| Bibliometrics | 0.007 | 0.016 |
| Science and technology studies | 0.005 | 0.004 |
| Scholarly communication | 0.004 | 0.006 |
| Open science | 0.011 | 0.006 |
| Research integrity | 0.006 | 0.009 |
| Insufficient payload (model declined to judge) | 0.001 | 0.003 |
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; both teacher heads agree on what is shown here.
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".