Solid-state to solution helicity inversion of pseudotetrahedral chiral copper(<scp>ii</scp>) complexes with 2,4-dihalo-salicylaldiminate ligands
Bibliographic record
Abstract
The enantiopure Schiff bases (R or S)-N-1-(phenyl)ethyl-2,4-X1,X2-salicylaldimine (X1, X2 = Cl, Br, I) coordinate to copper(ii) and provide pseudotetrahedral bis[(S or R)-N-1-(phenyl)ethyl-(2,4-X1,X2-salicylaldiminato-κ2N,O)]-Δ/Λ-Cu(ii) (Λ/Δ-Cu-R or Δ/Λ-Cu-S). An induced Λ and Δ-chirality at-metal centre has been launched along the C2-axis of the molecule. Steric constraints brought by halogen substituents on the coordinating salicylal ring provide diastereoselectively Λ-Cu-R or Δ-Cu-S as major and Δ-Cu-R or Λ-Cu-S as minor diastereomers at solid-state, as evidenced by X-ray crystal structures and PXRD analyses. These results reveal inversion of induced chirality at-metal in comparison to the similar complexes without halogen substituents on the salicylal ring. Electronic circular dichroism (ECD) spectra show mirror-image relationships, confirming enantiomeric excess of the R or S-ligated complexes in solution. Comparisons of experimental and simulated ECD spectra suggest diastereomeric excess of Δ-Cu-R or Λ-Cu-S in solution which correspond to an inversion from the found solid-state Λ-Cu-R or Δ-Cu-S as major diastereomers. In addition, the optimized gas-phase structures also reveal Δ-Cu-R or Λ-Cu-S as slightly more stable than Λ-Cu-R or Δ-Cu-S. Thus, solid-state versus solution (or gas-phase) studies also indicate an interconversion of induced chirality (helicity inversion) at-metal from Λ-Cu-R or Δ-Cu-S to Δ-Cu-R or Λ-Cu-S. Thermal stability increases with the molecular weight of the complexes following Cl < ClBr < Br < I substituents. Hirshfeld surface analyses explore the strongest halogen (ortho)-halogen (para) interactions between two molecules in Λ-Cu-R3 or Δ-Cu-S3 at a distance shorter than the sum of the van der Waals radii of the two iodine atoms, provide a brilliant red spot on the dnorm surfaces. EPR spectra along with simulation suggest an axial symmetry with gz > gx,y > 2.0 and values for gz/Az ≥ 135 cm indicate pseudotetrahedral geometry for the complexes.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.000 | 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".