Intermolecular C–H Activations of Hydrocarbons Initiated by Cp*M(NO)(CH<sub>2</sub>CMe<sub>3</sub>)(η<sup>3</sup>-CH<sub>2</sub>CHCHPh) Complexes (M = Mo, W)
Bibliographic record
Abstract
Thermolysis of Cp*W(NO)(CH 2 CMe 3 )(η 3 -CH 2 CHCHPh) ( 1 ) at 55 °C leads to the loss of neopentane and the formation of the 16e η 2 -allene intermediate complex Cp*W(NO)(η 2 -CH 2 ═C═CHPh) ( A ), which has been isolated as its 18e PMe 3 adduct ( 2 ). Further support for the existence of the allene intermediate A is provided by the thermolysis of 1 in cyclohexene, which affords Cp*W(NO)(H)(η 3 -CH 2 C(3-cyclohexenyl)CHPh) ( 3 ) as the principal organometallic product. In the presence of n -heptane, n -octane, or n -pentane, A effects C–H activations of the hydrocarbons exclusively at their terminal carbons and forms 18e Cp*W(NO)( n -alkyl)(η 3 -CH 2 CHCHPh) complexes ( 4 – 6 ). Similarly, treatments of 1 with mesitylene, methylcyclohexane, and ethylcyclohexane all lead to the corresponding primary sp 3 C–H activation products ( 7 – 9 ). Complex mixtures of organometallic products result when 1 is thermolyzed in p -xylene and toluene, reflecting the occurrence of both aryl and benzylic C–H activations. Interestingly, the aryl C–H activations do not afford the expected Cp*W(NO)(aryl)(η 3 -CH 2 CHCHPh) products but rather their Cp*W(NO)(H)[η 3 -CH(aryl)CHCHPh] isomers resulting from aryl–H exchange. The thermal chemistry of the molybdenum analogue of 1, namely Cp*Mo(NO)(CH 2 CMe 3 )(η 3 -CH 2 CHCHPh) ( 14 ), has also been investigated, and it turns out to be much more limited in scope. When 14 is heated at 35 °C in neat mesitylene for 22 h, it results in conversion to the mesitylene-activated product Cp*Mo(NO)(CH 2 C 6 H 3 -3,5-Me 2 )(η 3 -CH 2 CHCHPh) ( 15 ) in low yield, but thermolyses of 14 in other hydrocarbons do not produce tractable organometallic materials. The results of DFT calculations on the model reaction of CpW(NO)(η 2 -CH 2 ═C═CHMe) with propane confirm that the rate-determining step is the cleavage of a propane C–H bond and that the lower energy anti conformers favor terminal activation by 11.5 kJ/mol. 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 X-ray crystallographic analyses.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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; both teacher heads agree on what is shown here.
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".