Group Transfer Polymerizations of Acrylates Catalyzed by Mononuclear Early d-Block and f-Block Metallocenes: A DFT Study
Bibliographic record
Abstract
We present a DFT study of the monometallic group transfer polymerization (GTP) of methyl acrylate (MA) catalyzed by Sm-based and Zr-based metallocenes. The processes examined are the generation of the catalytically active species, the subsequent C−C coupling reaction, and the ring opening of a metallacyclic stable intermediate, resting state of the polymerization process, obtained from the C−C coupling. The mechanism for a neutral zirconocene, a cationic zirconocene, and a neutral samarocene are compared. The isoelectronic neutral samarocene and cationic zirconocene systems share many features, which explains their similar behavior in both the C−C coupling (no energy barrier on the potential energy surface) and the MA-assisted opening of the metallacycle. An analysis of the factors driving polymer stereoregularity in the processes catalyzed by the neutral samarocene and the cationic zirconocene has led to identifying a relationship between stereoregularity and the relative disposition of the acrylate and enolate ligands, as well as the direction of the incoming MA molecule in the opening of the metallacycle resting state. On the basis of these discoveries a kinetic model has been developed, which has proved successful in qualitatively predicting stereoregularity.
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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) | 0.003 | 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".