Diiminopyrrolide Copper Complexes: Synthesis, Structures, and <i>rac</i>-Lactide Polymerization Activity
Bibliographic record
Abstract
2,5-Diiminopyrrole ligands with N -xylyl (L3), N -naphthyl (L4), N -cyclohexyl (L5), N -diphenylmethyl (L6), and N - p -bromobenzyl (L7), as well as the 5-R-2-iminopyrroles with N - S -methylbenzyl (L8, R = H; L10, R = Me; L11, R = Cl) and N -benzyl (L9, R = H) were reacted with Cu(OMe) 2 and pyridylmethanol (R 1 OH) or dimethylaminoethanol (R 2 OH) to yield the corresponding dinuclear complexes L 2 Cu 2 (μ-OR) 2 . Reactions in the absence of chelating R 1 OH or R 2 OH only yielded homoleptic L 2 Cu or L 2 Cu 2 . Complexes with R 2 OH were obtained with all ligands but L4, complexes with R 1 OH for all ligands but L3, L4, and L6. All complexes but those with L7 displayed dinuclear crystal structures with pentacoordinated copper centers and bridging alkoxy groups. The alkoxy group and the pyrrolide ligand were consistently found in equatorial positions. Imine, pyridine, or amine occupied the axial position. L7 coordinated both imino groups to copper, yielding a distorted-octahedral coordination geometry. All complexes containing R 1 OH, with the exception of L7, showed an isotactic bias in the polymerization of rac -lactide, with a maximum P m value of 0.7. Complexes containing R 2 OH provided atactic PLA or, in the case of L3 and L6, heterotactic PLA. Reduced stereocontrol in monoiminopyrrolide copper complexes and lack of stereocontrol with octahedrally coordinated L7 indicate that the catalytic site needs to adapt to chain-end chirality and is participating in enantiomer selection.
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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".