Nickel Indenyl Complexes as Catalysts for the Dimerization and Polymerization of Ethylene
Bibliographic record
Abstract
The nickel indenyl compounds Ind(PR 3 )Ni-X (Ind = indenyl and its substituted derivatives; R = Ph, Cy, Me; X = Cl, Me, CCPh) can dimerize and/or polymerize ethylene in the presence of suitable activators. For example, poly(methylaluminoxanes) (PMAO) combine with these Ni precursors to produce catalytically active species for both the dimerization and polymerization of ethylene. The polymers obtained from these reactions are mostly linear polyethylenes which contain a small number of ethyl branches and exhibit molecular weights in the range of M w = 10 5 ( M w / M n ca. 2). On the other hand, using activators such as AgBF 4, AlCl 3, and B(C 6 F 5 ) 3 leads to the exclusive formation of butenes. It is proposed that the latter activators convert the Ni precursors to the highly electrophilic cations [IndNi(PR 3 )] +, which efficiently catalyze the dimerization of ethylene to butenes; in contrast, Ni/PMAO combinations give both the aforementioned cationic species as well as neutral species bearing a Ni(μ-Me)Al core, which is thought to be the active site for the polymerization reactions.
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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 | 0.001 | 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".