Intermolecular C–H Activations of Hydrocarbons Initiated by a Tungsten Trimethylsilylallyl Complex
Bibliographic record
Abstract
Thermolysis of Cp*W(NO)(Npt)(η 3 -CH 2 CHCHSiMe 3 ) [Cp* = η 5 -C 5 Me 5; Npt = CH 2 CMe 3 ] at 55 °C leads to the loss of neopentane and the formation of the 16-electron η 2 -allene intermediate Cp*W(NO)(η 2 -CH 2 ═C═CHSiMe 3 ), which activates hydrocarbons at their methyl groups. In the case of linear alkanes, only terminal C–H activation occurs. This selectivity persists in the presence of an ether functionality, but not with other oxygen-containing substrates such as aldehydes and alcohols. With these latter substrates, the organometallic complex is oxidized to Cp*W(O) 2 (Npt). The existence of the allene intermediate has been confirmed by its reaction with PMe 3 to form the 18-electron adduct and by its diagnostic reaction with cyclohexene. Carbonylation of Cp*W(NO)(Npt)(η 3 -CH 2 CHCHSiMe 3 ) with CO (550 psig) at room temperature results in the clean formation of the corresponding Cp*W(NO)(η 1 -C(═O)Npt)(η 3 -CH 2 CHCHSiMe 3 ) complex, which exists as a mixture of two interconverting isomers differing in their modes of attachment of the (η 3 -CH 2 CHCHSiMe 3 ) ligands to the tungsten centers. The congeneric molybdenum complex, Cp*Mo(NO)(Npt)(η 3 -CH 2 CHCHSiMe 3 ), has also been synthesized, and although it generates the requisite η 2 -allene intermediate upon thermolysis, its preferred mode of reactivity is coupling of the allyl and alkyl ligands. Consequently, the molybdenum complex is inferior to the tungsten system for effecting C–H activations. 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".