Tris(indenyl)lanthanoid Complexes (Ln = La, Pr, Nd) Containing either (S)-(−)-Nicotine or Two Simpler Pyridine Bases
Bibliographic record
Abstract
Novel examples of the complex of the type [Ln(Ind)3·Nic] [Ind = indenyl; Nic = (S)-(−)-nicotine] with Ln = La (2), Pr (3), and Nd (4) have been synthesised, along with their “parent” system [LaCp3·Nic] (1). Complexes 2−4 were structurally, exhaustively characterised (XRS, 1H NMR spectroscopy). Attempts to prepare homologues of 3 with achiral N-bases, pyridine, α-picoline, β-picoline, 2,6-dimethylpyridine, 2,6-bis(tert-butyl)pyridine, 2,2′-bipyridine, and 4,4′-dimethyl-2,2′-bipyridine, were successful with only the two least bulky bases, pyridine and β-picoline, which afforded the new adducts 5 and 6, respectively. The chiral [Ln(Ind)3·Nic] adducts are virtually isostructural, although subtle but systematic conformational variations emerge from the crystal structure analyses. While the unit cells of 2−4 contain two epimeric diastereomers, those of 5 and 6 involve genuine optical antipodes. The chiral carbon atom of nicotine lies approximately twice as far from the metal centre than the chiral sulfur atom of the methyl tolyl sulfoxide (MTSO) ligand in the previously reported [Ln(Ind)3·MTSO] systems. As a result of this, the impact of the chiral MTSO ligand, both on the molecular structure and the 1H NMR spectra, is found to be notably stronger than that of (S)-(−)-nicotine. The comparatively weak f-f circular dichroism of 3 is also compared with that of its (S)-(−)-MTSO-containing congener.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.017 | 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".