Isostructural Bis-1,2,3-Thiaselenazolyl Dimers
Bibliographic record
Abstract
Reduction of the N-methylated bis-1,2,3-thiaselenazolylium salts [2a,b,c][OTf] (with R(1) = Me and R(2) = H (2a), F (2b), Me (2c)) affords the corresponding bis-1,2,3-thiaselenazolyl radicals 2a,b,c. The radicals crystallize as centrosymmetric Se-Se sigma-bonded dimers [2a,b,c](2), in which an intramolecular Se-S bond of the radical is cleaved and replaced by an intermolecular Se-Se bond. The crystal structures of the three dimers are isomorphous, all belonging to the monoclinic space group P2(1)/c, and consist of interpenetrating, cross-braced, slipped pi-stack arrays laced together by numerous short intermolecular Se-N' and Se-S' contacts. In the solid state the dimers are diamagnetic, and behave as small band gap semiconductors with a room temperature conductivity sigma(RT) near 10(-6) S cm(-1). Application of pressure leads to a dramatic increase in conductivity for all three compounds. At 5 GPa the value of sigma(RT) ranges from near 10(-1) S cm(-1) for [2c](2) to 1 S cm(-1) for [2b](2) and 10(1) S cm(-1) for [2a](2). Comparison of the three crystal structures suggests that the compressibility of [2a](2), and hence the response of its conductivity to pressure, is superior to that of [2b,c](2).
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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) | 0.002 | 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".