Phosphine-Catalyzed C(sp2)–H Bond Activation with a Heterometallic Nickel---Aluminum Complex
Bibliographic record
Abstract
Herein we present the discovery of a ligand-catalyzed bond breaking and making processes that occurs in the coordination sphere of a novel Ni–Al heterometallic complex. While combinations of Ni pre-catalysts and Al additives are known for site-selective C–H functionalisation, detailed studies of such systems are rare. Combining [Ni(COD)2] and a molecular aluminum dihydride [(BDI)AlH2] (1; BDI = 2,6-diisopropylphenyl-beta-methyldiketiminate), results in facile formation of a Ni–Al heterometallic complex [(COD)Ni{H)2Al(BDI)}] (2; COD = 1,5-cyclooctadiene). Once generated, this species can effect the C(sp2)–H activation of 4-dimethylaminopyridine (DMAP) or pyridine with concomitant H2 evolution; a process that is accelerated through addition of an exogenous phosphine ligand, PCy3. Intimate steps of the mechanism of C(sp2)–H bond activation and H2 elimination were studied through kinetics, kinetic isotope effects (KIEs), isotope labelling studies, and computational modeling. The reaction is 1st order in PCy3 and proceeds with a low KIE of 0.9-1.1. Support is provided for a mechanism involving stepwise oxidative addition and reductive elimination processes that require the synergistic action of both metals, promoted by reversible coordination of the phosphine. These data strongly suggest that both C–H activation and H2 reductive elimination steps in this system are low energy and readily accessible and are not rate limiting. This finding has implications for future catalyst design using the synergistic behavior of Ni and Al metals and suggests that choice of ligand and control of ligand exchange steps, may well be the most important consideration in determining the rate of reaction.
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 | 0.000 | 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".