Multiple C–H Activations of Linear Alkanes by Various (η<sup>5</sup>-Cyclopentadienyl)W(NO)(CH<sub>2</sub>CMe<sub>3</sub>)<sub>2</sub> Complexes
Bibliographic record
Abstract
As illustrated in the accompanying diagram, thermolysis of Cp*W(NO)(CH 2 CMe 3 ) 2 (Cp* = η 5 -C 5 Me 5 ) at 80 °C in neat linear alkanes effects three successive C–H bond activations of the hydrocarbon substrates and forms Cp*W(NO)(H)(η 3 -allyl) complexes in which the allyl ligands are derived from the alkanes. These allyl hydrido compounds exist in solutions as mixtures of isomers containing monosubstituted (i.e., terminal) or 1,3-disubstituted (i.e., internal) allyl ligands which can have either an endo or exo orientation with the substituent groups being either proximal or distal to the nitrosyl ligand. Due to steric factors the most abundant isomer in all cases has a monosubstituted allyl ligand in the endo orientation with the alkyl end distal to the nitrosyl ligand. In addition, the relative abundance of Cp*W(NO)(H)(η 3 -allyl) isomers having monosubstituted allyl ligands decreases with increasing length of the n -alkane chain. Further thermolysis of the Cp*W(NO)(H)(η 3 -allyl) complexes results in the liberation of alkenes. Whether initiated by Cp*W(NO)(CH 2 CMe 3 ) 2 or independently synthesized Cp*W(NO)(H)(η 3 -allyl) complexes, the n -alkane dehydrogenations generally result in the preferential formation of 1-alkenes. They are stoichiometric, and their outcomes are not significantly affected by varying the experimental conditions employed (e.g., time, temperature, an open system, use of an H 2 acceptor, etc.) or by changing the initial bis(neopentyl) tungsten reactant to its Cp Et (η 5 -C 5 Me 4 Et) and Cp i Pr (η 5 -C 5 H 4 i Pr) analogues or to Cp*Mo(NO)(CH 2 CMe 3 ) 2 . The results of DFT calculations are consistent with these dehydrogenations proceeding via 16e Cp*M(NO)(η 2 -alkene) (M = Mo, W) intermediates that are in equilibrium with their more stable 18e Cp*M(NO)(H)(η 3 -allyl) isomers. These intermediates facilitate the allyl ligand exchange reactions depicted in the accompanying diagram by functioning as internal hydrogen acceptors during the dehydrogenation of the linear alkanes. Thermolysis of the final hydrido allyl complexes liberates the desired alkenes.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.000 | 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; 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".