Controlled Radical Polymerization of Vinyl Acetate with Cyclopentadienyl Chromium β-Diketiminate Complexes: ATRP vs OMRP
Bibliographic record
Abstract
The ability of compounds CpCr II (nacnac Ar,Ar ) (Ar = Dipp, 1; Xyl, 2 ) to catalyze the atom transfer radical polymerization (ATRP) of vinyl acetate has been explored using methyl 2-chloropropionate as initiator. Polymerizations were also carried out under reverse ATRP conditions with thermal initiation by 2,2′-azobis(4-methoxy2,4-dimethylvaleronitrile) (V-70) in the presence of compounds CpCr III (nacnac Ar,Ar )Cl (Ar = Dipp, 3; Xyl, 4 ). All data suggest that these processes are in fact proceeding by organometallic-mediated radical polymerization (OMRP). Stoichiometric reactions between complex 2 and the chlorinated compounds CH 3 CH(Cl)COOCH 3, ClCH 2 COPh, CH 3 CHClOOCCH 3, ClCH 2 OOC t Bu, and ClCH 2 t Bu in the absence of monomer aid in the interpretation of the polymerization results. The first two substrates show rapid one-electron oxidative additions to generate 4 and O-bonded Cr III products, whereas the third and fourth substrates add much more slowly to generate 4 and C-bonded Cr III products; ClCH 2 t Bu does not react. DFT calculations on the competitive radical trapping processes (activation barriers and relative stability of the products) confirm the kinetic and thermodynamic preference for metal−carbon bond formation to generate the dormant species of OMRP.
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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) | 0.001 | 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 | 0.001 |
| 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".