Bistabilities in 1,3,2-Dithiazolyl Radicals
Bibliographic record
Abstract
New synthetic methods for heterocyclic 1,3,2-dithiazolyl (DTA) radicals have been developed, and trends in the molecular spin distributions and electrochemical properties of a series of DTA radicals are reported. The crystal structures of [1,2,5]thiadiazolo[3,4-f][1,3,2]benzodithiazol-2-yl (TBDTA) and [1,3,2]pyrazinodithiazol-2-yl (PDTA) have been determined. The structure of TBDTA (at 293 and 95 K) contains two molecules in the asymmetric unit, each of which generates pi-stacked arrays, one consisting of antiparallel chains of centrosymmetrically associated dimers, the other comprising parallel chains of unassociated radicals. The structure of PDTA (at 293 and 95 K) is simpler, consisting of slipped stacks of pi-dimers. Variable-temperature magnetic susceptibility (chi(P)) measurements on TBDTA indicate essentially paramagnetic behavior for the unassociated radical pi-stacks over the range 5-400 K. By contrast PDTA is diamagnetic at all temperatures below 300 K, but between 300 and 350 K the value of chi(P) follows a sharp and well-defined hysteresis loop, with T(C) downward arrow = 297 K and T(C) upward arrow = 343 K. These features are symptomatic of a regime of bistability involving the observed low temperature pi-dimer structure and a putative high-temperature radical pi-stack. A mechanism for the interconversion of the two phases of PDTA and related structures is proposed in which hysteretic behavior arises from cooperative effects associated with the breaking and making of a lattice-wide network of intermolecular S- - -N' and/or S- - -S' interactions.
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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) | 0.001 | 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".