Alternative Synthetic Methods for PEPPSI‐Type Palladium Complexes
Bibliographic record
Abstract
Abstract Alternative procedures are reported for the preparation of PEPPSI‐type palladium complexes (PEPPSI = pyridine‐enhanced precatalyst preparation stabilization and initiation) in good to excellent yields. One method involves the reaction of [(NHC)Pd(acac)Cl] complexes (NHC = N‐heterocyclic carbene, acac = acetylacetonate) with hydrohalides (HX; X = Cl, Br, I) of pyridine or 2,6‐lutidine. Two other one‐pot syntheses involve Pd(acac)2, the azolium salt and pyridine hydrohalide (or 2,6‐lutidine hydrohalide). The complexes were obtained as moisture‐ and air‐stable solids and were characterized by 1H and 13C NMR spectroscopy, CHN analysis, and IR spectroscopy. The various synthetic procedures and the yields of the desired products are discussed. The X‐ray structure of [1‐(2,6‐diisopropylphenyl)‐3‐(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene]Pd(acac)Cl (4c) is also reported.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".