Phosphinimide−Phosphinimide Ligands: New Bulky Ligands for Ethylene Polymerization Catalysts
Bibliographic record
Abstract
The phosphinimide−phosphines PPh 2 (NPR 3 ) (R = i -Pr 1, t- Bu 2 ) were readily prepared in 80−98% yield. These species react with AlMe 3 or B(C 6 F 5 ) 3 to form Me 3 AlPPh 2 (NPR 3 ) (R = i -Pr 3, t- Bu 4 ) and (C 6 F 5 ) 3 B(PPh 2 (NP i -Pr 3 )) ( 5 ), respectively. Oxidation of compounds 1 and 2 with Me 3 SiN 3 yields Me 3 SiNPPh 2 (NPR 3 ) (R = i -Pr 6, t- Bu 7 ). These species react with CpTiCl 3 to give titanium(IV) complexes CpTiCl 2 (NPPh 2 (NPR 3 ) (R = i -Pr 8, t- Bu 9 ) and subsequently the alkylated complexes CpTiMe 2 (NPPh 2 (NPR 3 )) (R = i -Pr 10, t- Bu 11 ). Compounds 8 − 11 were tested for activity in ethylene polymerization. In the presence of excess methylalumoxane, the species 8 and 9 gave rise to active single-site catalysts, generating 299 and 34 gPE mmol - 1 h - 1, respectively. In contrast, activation of 10 and 11 by [Ph 3 C][B(C 6 F 5 ) 4 ] showed negligible polymerization activity. Reaction of 11 with B(C 6 F 5 ) 3 was shown to give numerous products, one of which was the dicationic species [CpTi(μ-Cl)(NPPh 2 (NP t -Bu 3 )] 2 [BC 6 F 5 ) 4 ] 2, 12 . The formation of this species and the implications of these results for catalyst and ancillary ligand design are considered and discussed. X-ray crystallographic data are reported for 1, 3, 4, 8, and 12 .
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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) | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".