Preparation of Dinuclear Phosphine-Bridged Palladium(II) Species and Their Silica-Bound Analogues as Catalysts for the Cyclization of Aminoalkynes
Bibliographic record
Abstract
Two new dinuclear palladium complexes, [Pd 2 Me 2 Cl 2 (dmpm) 2 ] ( 4 ) and [PdMe(Cl)(dmpm) 2 PdCl 2 ] ( 5 ), have been prepared and their structures determined by single-crystal X-ray analysis. 5 is an interesting example of a complex with both a cis -PdCl 2 center and a trans- MePdCl center, within the same molecule. The reactivity of 4, as well as the previously reported complexes [Pd 2 Me 2 Cl 2 (dppm) 2 ] ( 1 ), [Pd 2 ( μ -CH 2 )Cl 2 (dppm) 2 ] ( 2 ), and [Pd 2 Me 4 (dmpm) 2 ] ( 3 ), toward silica have been investigated. The complexes react readily with either dichloromethane or benzene suspensions of silica to give chemisorbed species, presumably by reaction of the Pd−Me group with the O−H bond of the surface silanol groups, in the case of 1, 3, and 4, and protonation of the methylene bridge, in the case of 2 . The complexes containing the more basic phosphine, dmpm, gave much higher palladium loadings (wt % Pd 1.37−2.47) on silica, compared to the dppm complexes (wt % Pd 0.55−0.80). The molecular and grafted materials were initially tested as catalysts for the cyclization of 6-aminohex-1-yne to give 2-methyl-1,2-dehydropiperidine. The silica/dmpm complexes were found to be the most active catalysts for this reaction and were also tested for the cyclization of 5-phenyl-4-pentyn-1-amine.
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".