Configurationally flexible zinc complexes as catalysts for <i>rac</i>-lactide polymerisation
Bibliographic record
Abstract
Zn(N(SiMe3)2)2 was reacted with pyridinemethanol and R,R-N,N'-di(methylbenzyl)-2,5-diiminopyrrole (L1H) to afford the dimeric complex (L1)2Zn2(μ-OR)2. The complex showed moderate activity in rac-lactide polymerization to heterotactic polymer (Pr = 0.75). 2,4-Di-tert-butyl-6-aminomethyl-phenol ligands with amino = N,N,N',N'-tetramethyldiethylenetriamine (L2H) or di-(2-picoly)amine (L3H) were reacted with ZnEt2 to form (L2)ZnEt and with Zn(N(SiMe3)2)2 to form the respective amide complexes. All complexes, including (L1)2Zn2(μ-OR)2 were characterised by X-ray diffraction studies. (L2)ZnEt was unreactive toward ethanol, but the amide complexes afforded (L2)ZnOEt and (L3)ZnOEt upon reaction with ethanol, which were used in rac-lactide polymerization without isolation. All complexes racemise readily at room temperature and show apparent Cs-symmetry in their NMR spectra. The ethoxide complexes were highly active in lactide polymerization, with (L3)ZnOEt reaching full conversion in 15 min at 0.5 mM catalyst concentration at room temperature. In both cases, introduction of a second donor arm on the central nitrogen introduced a slight bias for isotactic monomer enchainment (Pm = 0.55-0.60), which for (L3)ZnOEt was dependent on catalyst concentration.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".