A Chiral Bis(oxazoline) Phosphine with a Rigid Backbone: Ligand Synthesis and Characterization of Products Obtained in Highly Diastereoselective Reactions with a Rhodium(I) Complex and a Tetrahedral “RhRu<sub>3</sub>” Cluster
Bibliographic record
Abstract
A novel bis(oxazoline)−thienylphosphine ligand ( 3, abbreviated as ( S, S )-BOTPHOS) has been synthesized in an enantiomerically pure S, S state and spectroscopically characterized. The reaction of 3 with Rh 2 (CO) 4 Cl 2 in a dichloromethane solution affords the mononuclear Rh(Cl) 2 (CH 2 Cl)(κ 3 -( S, S )-BOTPHOS) octahedral complex ( 4 ), containing BOTPHOS coordinated to the Rh(III) center in a mer mode through the phosphorus atom and the two nitrogens of the oxazoline fragments. The coordination sphere of this complex displays an unusual rigidity, which is determined by intramolecular hydrogen bonding between the chlorides and protons of the organic ligands. Treatment of the CpRhRu 3 (H) 2 (CO) 10 cluster with a slight excess of ( S, S )-BOTPHOS results in the substitution of two carbonyls at a ruthenium atom and chelate coordination of the ligand through the phosphorus and a nitrogen atom of an oxazoline ring to give CpRhRu 3 (H) 2 (CO) 8 (κ 2 -( S, S )-BOTPHOS) ( 5 ). The bidentate coordination mode of BOTPHOS makes the phosphorus atom of this ligand chiral and simultaneously differentiates the ruthenium vertexes in the tetrahedral RhRu 3 cluster. This differentiation generates an asymmetry in the cluster framework and introduces a fourth chiral center in the cluster molecule. A specific feature of this reaction consists of the quantitative diastereoselection induced by the chirality of the BOTPHOS oxazoline fragments. This induction produces only S configurations in both of the new chiral elements generated in the cluster molecule. Molecular structures of the complexes obtained have been established by X-ray crystallography and have been confirmed by the NMR spectroscopic study of these compounds in solution. CD spectroscopic measurements of 3 − 5 indicate that these compounds have been obtained in their enantiopure state.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".