Donor-Induced Decomposition of the Grubbs Catalysts: An Intercepted Intermediate
Bibliographic record
Abstract
The σ-alkyl species RuCl 2 (CH 2 PCy 3 )(py) 3 ( 3a ) is intercepted on adding pyridine to the first-generation Grubbs catalyst 1a during RCM or to the isolated resting-state species RuCl 2 (PCy 3 ) 2 (═CH 2 ) ( 2a ). Complex 3a is formed by pyridine-induced displacement of PCy 3 and nucleophilic attack of the liberated PCy 3 on the methylidene carbon. The rapid, near-quantitative conversion of 2a into 3a indicates that nucleophilic attack by PCy 3 is the primary deactivating event. Once formed, 3a decomposes more slowly via several competing pathways. One such pathway involves elimination of the σ-alkyl ligand as [CH 3 PCy 3 ]Cl ( A ), following proton and chloride abstraction. Observation of nearly 80% 3a during RCM by 1a in the presence of pyridine confirms the relevance of this behavior to metathesis and implicates the resting-state methylidene 2a as the vulnerable species, rather than the metallacyclobutane intermediate. Any donor capable of displacing PCy 3 and stabilizing a five-coordinate methylidene adduct is predicted to trigger the same deactivation sequence, steric factors permitting.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".