General Synthesis of Cyclopentadienylchromium(II)<i>η</i><sup>3</sup>-Allyl Dicarbonyl Complexes
Bibliographic record
Abstract
Thermally stable chromium(II) dicarbonyl complexes bearing substituted η 3 -allyl and η 5 -cyclopentadienyl ligands have been prepared via oxidative addition of the allyl bromide to tris(acetonitrile)tricarbonylchromium at −30 °C in acetonitrile, followed by in situ addition of the ancillary cyclopentadienyl ligand anion at low temperature. Spectroscopic data for allyl complexes 1, 2, and 4 − 7 indicate that the solution configuration of the allyl ligand is preferentially exo, while the data for the 2-methylallyl derivative 3 suggest the formation of a 65:35 mixture of endo and exo isomers. The cyclohexenyl and indenyl complexes 5 and 7, respectively, exhibit interesting spectroscopic and structural characteristics. While most complexes were prepared in good yield, the addition of sterically larger ancillary ligands was problematic: the addition of indenyllithium led to low yields of the allylchromium complex, while treatment with (pentamethylcyclopentadienyl)lithium led to the isolation of only organic products. These diminished returns are attributed to attack of the ancillary ligand anion directly on the coordinated allyl ligand of the intermediate formed by oxidative addition. Solid-state structures of the η 3 -allyl, crotyl, and cyclohexenyl complexes, all in the exo configuration, have been determined by X-ray crystallography.
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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) | 0.001 | 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) | 0.006 | 0.002 |
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".