Synthesis, Structures, and Ethylene Oligomerization Activity of Bis(phosphanylamine)pyridine Chromium/Aluminate Complexes
Bibliographic record
Abstract
A trivalent chromium complex of a PN(pyridine) ligand system, {[(2,6-Ph 2 P-NH) 2 C 5 H 3 N]CrCl 3 }(THF) 2 ( 1 ), was prepared and tested as a catalyst for ethylene oligomerization and polymerization, with the purpose of probing the ability of a pyridine ring substituent as a stabilizing factor on catalytically active intermediates. Its nonselective catalytic behavior indicated that ready reduction of the metal center to the divalent state occurred during the activation process. To substantiate this point, we have reacted 1 with a few common aluminate activators and isolated both the divalent complexes {[2,6-Ph 2 PNHC 5 H 3 NAlClEt 2 NPPh 2 ]Cr(μ-Cl) 2 AlEt 2 }(toluene) ( 3 ) and {[2,6-Ph 2 PNHC 5 H 3 NAlCl- i -Bu 2 NPPh 2 ]Cr(μ-Cl) 2 Al- i -Bu 2 } 2 (toluene) ( 4 ) and the trivalent complexes {[2,6-Ph 2 PNHC 5 H 3 NAlClMe 2 NPPh 2 ]CrMe(μ-Cl) 2 AlMe 2 }(toluene) 1.5 ( 2 ) and {[2,6-Ph 2 PNHC 5 H 3 NHNPPh 2 ]CrEt(μ-Cl) 2 AlEt 2 }AlEtCl 3 (hexane) 0.5 ( 5 ). The reaction of the ligand with the divalent chromium precursor CrCl 2 (THF) 2 in the presence of alkylaluminum afforded {[2,6-Ph 2 PNHC 5 H 3 NCl 2 EtAlNPPh 2 ]Cr(μ-Cl) 2 AlEt 2 } 2 (toluene) ( 6 ) containing aluminate residues, where the metal has preserved the initial divalent state. All of these species showed moderate to high activities toward ethylene oligomerization.
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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 | 0.000 |
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 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".