Silica-Grafted Borato Cocatalysts for Olefin Polymerization Modeled by Silsesquioxane−Borato Complexes
Bibliographic record
Abstract
The syntheses and reactivity studies of silsesquioxane−borato complexes are described. Treatment of B(C 6 F 5 ) 3 with (c-C 5 H 9 ) 7 Si 8 O 12 (OH) and (c-C 5 H 9 ) 7 Si 7 O 9 (OH) 3 in the presence of a Brønsted base yields the silsesquioxane−borates X + {[(c-C 5 H 9 ) 7 Si 8 O 13 ]B(C 6 F 5 ) 3 } - ( 1a, X + = PhN(H)Me 2 +; 1b, X + = Et 3 NH + ) and X + {[(c-C 5 H 9 ) 7 Si 7 (OH) 2 O 10 ]B(C 6 F 5 ) 3 } - ( 1b, X + = PhN(H)Me 2 +; 2b, X + = Et 3 NH + ), respectively. When the more nucleophilic base pyridine is used, (C 6 F 5 ) 3 B·NC 5 H 5 ( 3 ) is formed instead, demonstrating the competition between B(C 6 F 5 ) 3 and H + to react with the amine. The dimethylaniline in 1a and 2a is readily exchanged by NEt 3 to form 1b and 2b . With the nucleophilic Lewis base NC 5 H 5, the B−O bond in 1a and 2a is split, yielding (C 6 F 5 ) 3 B·NC 5 H 5 ( 3 ) and the free silsesquioxanes. Complexes 1 and 2 rapidly undergo hydrolysis under formation of the hydroxyl complexes X + {(C 6 F 5 ) 3 BOH} - ( 4a, X + = PhN(H)Me 2 +; 4b, X + = Et 3 NH + ). Likewise, alcoholysis of 1a and 2a with i -PrOH yields the alkoxide {PhN(H)Me 2 } + { i -PrOB(C 6 F 5 ) 3 } - ( 5 ). The B−O bond is only moderately stable toward early-transition-metal alkyls. Nevertheless, Cp 2 Zr(CH 2 Ph) 2 + 1a and Zr(CH 2 Ph) 4 + 2a form single-site ethylene polymerization catalysts. Detailed reactivity studies demonstrated that both B−O and B−C bond splitting plays a crucial role, as not 1a and 2a, but their decomposition product B(C 6 F 5 ) 3 is the actual cocatalyst. The solid-state structures of 1a and 4b were determined by single-crystal X-ray analysis.
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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) | 0.001 | 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".