Highly Active Ethylene Oligomerization Catalysts
Bibliographic record
Abstract
Reaction of RN(H)PBr(Ph) 2 N(H)R [R = t -Bu, i -Pr, Ph] with two equivalents of n -BuLi followed by reaction with CrCl 2 (THF) 2 afforded the divalent chromium complexes [( t -Bu)NP(Ph) 2 N( t -Bu)]Cr(μ 2 -Cl) 2 Li(THF) 2 ( 1 ), [( i -Pr)NP(Ph) 2 N( i -Pr)]Cr(μ 2 -Cl) 2 Li(THF) 2 ( 2 ), and [{[(Ph)NP(Ph) 2 N(Ph)]Cr} 2 (μ 2 -Cl) 3 ][Li(DME) 3 ] ( 3 ). The trivalent analogue of 1, {[( t -Bu)NP(Ph) 2 N( t -Bu)]Cr(μ 2 -Cl) 3 (μ 3 -Cl) 2 }{Li (THF) 2 } ( 4 ), was obtained in a similar manner via treatment of the double deprotonated ligand with CrCl 3 (THF) 3 . Both reactions of the divalent 1 or trivalent 4 with AlMe 3 yielded the trivalent and cationic complex {[( t -Bu)NP(Ph) 2 N( t -Bu)] 2 Cr}{(Me 3 Al) 2 Cl}·toluene ( 5 ). Upon activation with MAO, 1 – 3 produced unprecedented and potentially useful catalytic systems for nonselective ethylene oligomerization devoid of polymer. Divalent chromium is clearly the species responsible for the catalytic behavior, ruling out that nonselective oligomerization proceeds via a redox metallacycle mechanism. The absence of polymer in combination with the record activity makes 1 competitive with the best performing industrially used systems.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.075 | 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; 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".