Formation and Properties of a Novel Dinuclear, Cationic α-Diimine Palladium-Based Ethylene Polymerization Catalyst Containing a Pd−Pd Bond and Bridging Methylene and Methyl Groups
Bibliographic record
Abstract
The compound PdMe 2 (N∧N) (N∧N = ArN CMeCMe NAr, Ar = 2,6-C 6 H 3 ( i -Pr) 2 ) reacts with the methide abstractors B(C 6 F 5 ) 3, [Ph 3 C][B(C 6 F 5 ) 4 ], and [Ph 3 C][CF 3 SO 3 ] in the absence of ethylene to give the metal−metal-bonded, dinuclear, cationic complex [(N∧N)Pd( μ -CH 2 )( μ -Me)Pd(N∧N)] +, which is characterized by 1 H and 13 C{ 1 H} NMR spectroscopy, mass spectrometry, and X-ray crystallography. This cationic complex, with the three counteranions, reacts with ethylene to produce the same type of low-density polyethylene produced by the known catalyst [PdMe(solvent)(N∧N)] +, formed by methide abstraction from PdMe 2 (N∧N) by [H(Et 2 O) 2 ][B{3,5-C 6 H 3 (CF 3 ) 2 } 4 ]. Indeed, reaction of the dinuclear species with ethylene results in conversion to the mononuclear [PdMe(solvent)(N∧N)] +, which appears to be the true catalytic species. The three weakly coordinating counteranions [BMe(C 6 F 5 ) 3 ] -, [B(C 6 F 5 ) 4 ] -, and [B{3,5-C 6 H 3 (CF 3 ) 2 } 4 ] - differ little in their effects on the polymerization process, results consistent with the resting state for this catalytic system being the cationic ethylene complex [Pd(η 2 -C 2 H 4 )(∼polymer)(N∧N)] + . Interestingly, activation by [Ph 3 C][CF 3 SO 3 ] gives a catalyst of considerably reduced potency, suggesting that the triflate anion is a better ligand in this system and does compete effectively for the active site on the metal.
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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) | 0.001 | 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".