Vanadium-Promoted Aldol Condensation and Pinacolic Coupling of Acetylpyrrole: Formation of Two New Potent Dinuclear Catalysts for Olefin Copolymerization
Bibliographic record
Abstract
Reaction of VCl 3 (THF) 3 with 3 equiv of the potassium salt of acetylpyrrole, K[α-(CH 3 CO)C 4 H 3 N], afforded the dinuclear {V 2 [K(THF)] 2 [CH 3 CO(C 4 H 3 N)] 2 }[(C 4 H 3 N)C(O)CH 2 C(C 4 H 3 N)(CH 3 )O] 2 ( 1 ), where four acetylpyrrolide anions from two vanadium moieties have undergone an aldol condensation. The two pyrrolyl−acetylacetonate units so generated work as tetradentate binucleating ligands holding together the dinuclear structure. A similar reaction carried out on the divalent [V 2 Cl 3 (THF) 6 ] 2 [Zn 2 Cl 6 ] salt afforded the dinuclear and trivalent {VK(THF)[(C 4 H 3 N)C(O)CH 3 ]} 2 [(C 4 H 3 N)(CH 3 )(O)CC(O)(CH 3 )(C 4 H 3 N)]·0.5(toluene) ( 2 ), where two acetylpyrrolide ligands, one per vanadium atom, have undergone a reductive coupling to form a pinacol. Even in this case the dipyrrolylpinacol works as a tetradentate binucleating ligand holding together the dinuclear frame. Attempts to perform the same reaction on another V(II) salt such as VCl 2 (TMEDA) 2 (TMEDA = N, N, N ‘, N ‘-tetramethylethylenediamine) afforded instead the corresponding divalent derivative V(TMEDA)[(C 4 H 3 N)C(O)CH 3 ] 2 ( 3 ), where the acetylpyrrolide anions remained intact. Both 1 and 2 are potent olefin copolymerization catalysts upon activation with diethyl aluminum chloride, while 3 displays low but not negligible activity.
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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".