Thermal Chemistry of a Tungsten Trimethylsilylallyl Complex in Benzene and Fluorobenzenes
Bibliographic record
Abstract
The thermolysis of Cp*W(NO)(Npt)(η 3 -CH 2 CHCHSiMe 3 ) ( 1; Cp* = η 5 -C 5 Me 5; Npt = CH 2 CMe 3 ) in benzene at 55 °C generates three isomeric products having the composition Cp*W(NO)(H)(η 3 -Me 3 SiCHCHCHPh) ( 2 ). These are isomers of the expected Cp*W(NO)(Ph)(η 3 -Me 3 SiCHCHCH 2 ) compound and result from an intramolecular Ph/allyl H exchange. Thermolysis of 2 in the presence of pyridine produces the η 2 -olefin pyridine adduct Cp*W(NO)(η 2 -Me 3 SiCH 2 CH═CHPh)(C 5 H 5 N) ( 3 ). However, when the same reaction is carried out in deuterobenzene with 10 equiv of pyridine, NMR spectroscopic data suggest that the meso hydrogen of the allyl ligand is exchanged for a deuterium atom before pyridine trapping occurs. The activation of fluorobenzenes (i.e., pentafluorobenzene, p -difluorobenzene, and o -difluorobenzene) by Cp*W(NO)(Npt)(η 3 -CH 2 CHCHSiMe 3 ) has also been studied, and for these substrates, C–H bond activation occurs exclusively. Selectivity for the activation of these C–H bonds appears to be determined by sterics. Intramolecular migration of the newly formed fluoroaryl ligands onto the allyl ligands does not occur when there is a fluorine atom in the position ortho to the newly formed W–C bond. This behavior is probably a manifestation of the fact that metal– o -fluoroaryl bonds tend to be stronger than metal–aryl linkages. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.
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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) | 0.002 | 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".