The first observed complex of 11-crown-3 ether. X-ray crystal structure and NMR study of (benzo-11-crown-3)<sub>2</sub>·LiNCS
Bibliographic record
Abstract
The title complex crystallizes in the monoclinic P21/c space group, with a = 7.7397(8), b = 18.287(2), c = 17.4726(19) Å, β = 94.008(2)°, and Z = 4. The coordination geometry around the lithium cation is pseudooctahedral. The effects of lithium complexation on the 1H and 13C solution NMR spectra are discussed. In the solid-state 13C NMR spectrum at 300 K, very long aliphatic proton spin lattice relaxation times are observed along with broadening of the aliphatic carbon resonances. These results are attributed to the dipolar washout phenomenon, where the presence of a low amplitude motion of the same frequency as the 1H decoupler, leads to less effective removal of the 1H13C dipolar coupling. At 330 K, there is some sharpening of the aliphatic resonances since there is less interference between the motion and the decoupling frequency.Key words: crown ether analog, lithium complex.
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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) | 0.003 | 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".