Replacing Chloride by Alkoxide: Cp<sub>2</sub>Zr(H)OR, Searching for Alternatives to Schwartz's Reagent
Bibliographic record
Abstract
Attempts to synthesize zirconocene hydrido alkoxide species, Cp 2 Zr(H)OR, via several synthetic pathways consistently failed to yield the targeted complexes, which seem prone to undergo disproportionation into Cp 2 ZrH 2 and a bisalkoxide complex. Reaction of Cp 2 ZrH 2 with HOR, Me 3 SiOR, or Ph 2 CO yielded the corresponding bisalkoxide complexes Cp 2 Zr(OR) 2, of which Cp 2 Zr{OC(H)Ph 2 } 2 was characterized by an X-ray diffraction study. Insertion of vinyl ethers into Cp 2 ZrH 2 yielded Cp 2 Zr(OR) 2 and Cp 2 Zr(Et)OR. Attempted hydrogenation of Cp 2 Zr(Me)OR or reaction of Cp 2 Zr(BH 4 )OR with NEt 3 did not yield the targeted complexes. Cp 2 Zr(H)OC 6 H 5 and Cp 2 Zr(H)OC 6 F 5 could be obtained, however, as transient species by β-H elimination from Cp 2 Zr( t Bu)OR, ligand exchange between Cp 2 ZrH 2 and Cp 2 Zr(OC 6 F 5 ) 2, or protonation in the presence of olefin to yield the corresponding hydrozirconation products. In hydrozirconation reactions of styrene both species are highly regioselective. The alkoxide substituent failed to inhibit β-H elimination in hydrozirconations of trans -3-hexene or β-OR elimination in reactions with vinyl ethers. On the other hand, it imparted a vastly increased thermal stability to the tert -butyl complexes Cp 2 Zr( t Bu)OR, which were stable for up to several months in solution, before they isomerize to the respective isobutyl complexes. Cp 2 Zr( i Bu)OC 6 H 5 was characterized by X-ray crystallography.
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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 | 0.000 | 0.001 |
| 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) | 0.000 | 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 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".