Iron Phosphinimide and Phosphinimine Complexes: Catalyst Precursors for Ethylene Polymerization
Bibliographic record
Abstract
Reaction of Li[NP t -Bu 3 ] with FeCl 2 affords [Cl 3 Fe 2 (μ-NP t -Bu 3 ) 2 ] 1 in 71% yield. This mixed valent Fe(III)−Fe(II) undergoes reversibly one-electron oxidation to generate [Cl 3 Fe 2 (μ-NP t -Bu 3 ) 2 ] + . Chemical oxidation with [Cp 2 Fe]PF 6 yields [Cl 2 Fe(μ-NP t -Bu 3 )] 2 2 . The reaction of Li[NP t -Bu 3 ] with FeBr 3 affords [Br 4 Fe 2 (μ-NP t -Bu 3 ) 2 ] 3, while the reaction of FeCl 3 with Me 3 SiNPCy 3 gives [Cl 2 Fe(μ-NPCy 3 )] 2 4 . Hydrolysis of 3 yields the species [( t- Bu 3 PNH)Br 2 Fe] 2 (μ-O) 5 . These species have also been evaluated as catalysts for the polymerization of ethylene and copolymerization of ethylene/octene. These species were found to be single-site catalysts even under rather demanding conditions (50−160 °C, 100−300 psig ethylene), although the activities are generally low. Compound 5 affords polymer similar to that produced by 3, suggesting that MAO dehydrates 5 generating a catalyst similar to that derived from 3 . Compounds 1, 2, 4, and 5 have been crystallographically characterized.
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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) | 0.002 | 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; 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".