Ferrocenyl-Imidazolylidene Ligand for Redox-Switchable Gold-Based Catalysis. A Detailed Study on the Redox-Switching Abilities of the Ligand
Bibliographic record
Abstract
An imidazolium salt with a fused benzoferrocenyl was synthesized. This compound was used as an N-heterocyclic carbene (NHC) precursor, and the related ferrocenyl-imidazolylidene complexes Fc-NHC-ML n (ML n = IrCl(COD), IrCl(CO) 2, AuCl) were synthesized and fully characterized, including the crystallographic characterization of some of the key structures. The oxidation of the iridium carbonyl compound Fc-NHC-IrCl(CO) 2 with acetylferrocenium tetrafluoroborate afforded the oxidized ferrocenium-NHC-IrCl(CO) 2 (Fe(III)) species; however the isolated product contained a byproduct resulting from the protonation of the starting Fe(II) complex. The analysis of the electron-donating character of the neutral ligand and the ligand resulting from the oxidation was carried out by studying the variation of the ν(CO) stretching frequencies of Fc-NHC-IrCl(CO) 2 and its oxidized analogue, revealing that this shift is 2.9 cm –1, which is consistent with a decrease of the electron-donating character of the ligand produced by the generation of a positively charged metal complex. DFT calculations were carried out in order to rationalize these results. The effects of the oxidation of the ligand in homogeneous catalysis were tested by using a related ferrocenyl-imidazolylidene-gold(I) complex. In the hydroamination of terminal alkynes, the results indicated that the oxidation of the ligand produced a moderate increase of the activity of the gold catalyst. In the cyclization of alkynes with furans, the neutral complex was not active, while the product resulting from its oxidation produced moderate to good yields in the formation of the final products.
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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 | 0.001 | 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".