Mechanistic Analysis of Iridium(III) Catalyzed Direct CH Arylations: A DFT Study
Bibliographic record
Abstract
In a recent experimental work the Ir complex [Ir(cod)(py)(PCy(3))](PF(6)) (that is, Crabtree's catalyst) has been shown to catalyze the C-H arylation of electron-rich heteroarenes with iodoarenes using Ag(2)CO(3) as base. For this process, an electrophilic metalation mechanism, (S(E)Ar) has been proposed as operative mechanism rather than the concerted metalation-deprotonation (CMD) mechanism, widely implicated in Pd-catalyzed arylation reactions. Herein we have investigated the C-H activation step for several (hetero)arenes catalyzed by a Ir(III) catalyst and compared the data obtained with the results for the Pd(II)-catalyzed C-H bond activation. The calculations demonstrate that, similar to Pd(II)-catalyzed reactions, the Ir(III)-catalyzed direct C-H arylation occurs through the CMD pathway which accounts for the experimentally observed regioselectivity. The transition states for Ir(III)-catalyzed direct C-H arylation feature stronger metal-C((arene)) interactions than those for Pd(II)-catalyzed C-H arylation. The calculations also demonstrate that ligands with low trans effect may decrease the activation barrier of the C-H bond cleavage.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.018 | 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 teacher head, 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".