Isolation of a Chromium Hydride Single-Component Ethylene Polymerization Catalyst
Bibliographic record
Abstract
Reaction of the divalent complex [( t -Bu)NPN( t -Bu)] 2 Cr ( 1 ) with different stoichiometric ratios of Al( i -Bu) 3 afforded {μ-[( t -Bu)NP( i -Bu)N( t -Bu)]Al( i -Bu) 2 } 2 Cr ( 2 ) and [{( i -Bu)P{μ-N( t -Bu)} 2 Al( i -Bu) 2 }Cr(μ-H)] 2 ( 3 ) as part of the same reaction sequence. Complex 2 arises from association of alane and the two ligands via alkylation of the P atom and retention of the AlR 2 unit. Complex 3 appears to be generated from subsequent dissociation of one alkylated ligand and possible transfer of an i -Bu group to Cr followed by β-H elimination or transfer of a hydride originating from isobutyl elimination of the aluminum-containing residue. Both species are potent ethylene polymerization catalysts with no need for further activation. It is assumed that 2 is transformed in situ into 3 under the influence of ethylene. Reactions with ethylene carried out in the presence of excess of Al( i -Bu) 3 switch the selectivity completely toward selective trimerization.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.017 | 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 teacher head, 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".