Vibrational circular dichroism spectroscopy of two chiral binaphthyl diphosphine ligands and their palladium complexes in solution
Bibliographic record
Abstract
BINAP (2,2'-diphenylphosphino-1,1'-binaphthyl) is a unique binaphthyl diphosphine ligand with axial chirality. The palladium complexes of BINAP and of its derivative TOLBINAP have found extensive applications in the field of asymmetric syntheses. The conformational changes in the BINAP and TOLBINAP ligands before and after coordination with palladium have been investigated using density functional theory, vibrational absorbance (VA) and vibrational circular dichroism (VCD) spectroscopy. VA and VCD spectra of these two chiral ligands and their corresponding palladium complexes have been recorded in CDCl(3) solution. Extensive conformational searches have been carried out for both the ligands and the associated palladium complexes. Coordination with palladium has been found to introduce structural rigidity to the ligands. The calculated VA and VCD spectra of the ligands and complexes in the gas phase show substantial differences to the experimental data. Incorporation of the implicit polarisable continuum solvation model has provided much better agreement between theory and experiment, especially for the complexes, allowing clear identification of the species and conformations. This and the high specificity of VCD spectral signatures to chirality and to conformations suggest the potential applications of VCD spectroscopy for following these important catalytic species in solution reactions directly.
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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 | 0.001 |
| 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 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".