DFT Studies on the Copolymerization of α-Olefins with Polar Monomers: Comonomer Binding by Nickel- and Palladium-Based Catalysts with Brookhart and Grubbs Ligands
Bibliographic record
Abstract
Gradient-corrected density functional theory has been used to study the polar monomer binding mode in complexes with Ni- and Pd-based Brookhart-diimine (cationic) and Grubbs-salicylaldiminato (neutral) catalysts. Methyl acrylate and vinyl acrylate, as well as their fluorinated derivatives, have been studied as the comonomers in the copolymerization with α-olefins. Two binding modes have been considered: the π-complexes in which a polar monomer is bound by its olefinic functionality, and the O-complexes with a monomer bound by its carbonyl oxygen. The role of the electronic and the steric effects has been investigated, by considering the simplified (generic) models and the examples of the real catalysts. An energy decomposition of the contributions to the binding energies has been performed. The results show that for the Pd-based Brookhart system (active copolymerization catalyst) the π-complex is preferred, while for its Ni analogue (inactive) the O-complex is more stable. Further, the difference between Ni- and Pd-systems has mainly a steric (electrostatic + Pauli repulsion) origin: there is practically no difference in the orbital-interaction contribution to the binding energy between Ni- and Pd-based systems, as far as a comparison between the two binding modes is concerned. For the fluorinated monomers, the preference of the O-complex is decreased or reversed. However, the binding energies of both the π- and O-complexes are affected. In the complexes with Grubbs catalyst the π-complexes are strongly preferred for both the Ni- and Pd-based systems. The presence of bulky substituents on the catalysts results in a decrease in the binding energies of both the π- and O-complexes; the preference of the binding mode is not affected. Finally, the relative binding constants of the ethylene, propylene, and acrylate in the complexes involving the real Pd-Brookhart system agree with the experimental data for a similar catalyst: the ethylene complexes are most stable, followed by those of propylene and acrylate.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".