Reactions of Grubbs Catalysts with Excess Methoxide: Formation of Novel Methoxyhydride Complexes
Why this work is in the frame
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Bibliographic record
Abstract
On exposure to NaOMe (≥3 equiv) in CH 2 Cl 2 –MeOH at 23 °C, the first-generation Grubbs catalyst RuCl 2 (PCy 3 ) 2 (═CHPh) ( 1a ) is immediately transformed into the six-coordinate methoxyhydride complexes RuH(OMe)(CO) 2 (PCy 3 ) 2 ( 4a ) and RuH(OMe)(CO)(H 2 )(PCy 3 ) 2 ( 5a ). Complex 5a can be recycled into 4a under conditions conducive to removal of H 2 . The second-generation catalyst RuCl 2 (IMes)(PCy 3 )(═CHPh) ( 1b; IMes = N,N ′-bis(mesityl)imidazol-2-ylidene) reacts more slowly, requiring several hours even at 20 equiv of NaOMe, and terminates at five-coordinate RuH(OMe)(CO)(IMes)(PCy 3 ) ( 3b ). Experiments in the presence of added PCy 3 reveal that consumption of 1a, but not 1b, proceeds via the four-coordinate intermediate formed by equilibrium loss of phosphine, a function of the lability of the PCy 3 ligand at ambient temperatures. The poor accessibility of such an intermediate for 1b at 23 °C retards salt metathesis and inhibits further reaction of 3b . For the bis(PCy 3 ) analogue 3a, fast transformation into 4a is proposed to involve reversible loss of PCy 3, coordination of methanol, σ-metathesis of methanol at the hydride site to liberate H 2, and β-elimination/decarbonylation of bound methoxide. Competitive uptake of H 2 by 3a yields six-coordinate 5a (the dihydrogen adduct of 3a ). Independent routes to RuH(OMe)(CO) 2 (L)(PCy 3 ) ( 4a/b; a, L = PCy 3; b, L = IMes) were developed: these involved sequential transformation of RuHCl(CO)(L)(PCy 3 ) ( 2a/b ) into the bis-carbonyl adducts RuHCl(CO) 2 (L)(PCy 3 ) ( 7a/b ) under CO, conversion of 7a/b into the more reactive triflates RuH(OTf)(CO) 2 (L)(PCy 3 ) ( 8a/b ), and reaction of 8a/b with equimolar NaOMe. Dihydride 6b was also prepared, by reaction of 8b with NaH.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.001 | 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 it