Structural, Magnetic and DFT studies on a Charge‐Transfer Salt of a Tetrathiafulvalenepyridyl‐(1,5‐diisopropyl) verdazyl Diradical Cation
Bibliographic record
Abstract
Abstract A new tetrathiafulvalene (TTF) donor covalently appended with a 1,5‐diisopropylverdazyl radical through a cross‐conjugated pyridyl linker ( 3 ) has been prepared and characterised. Reaction of 3 with tetracyanoquinonedimethane (TCNQ) afforded the 2:1 charge‐transfer complex ( 3 ) 2 ⋅ TCNQ ( 4 ), in which the IR and structural data are consistent with 0.25 e − charge transfer from the TTF donor (D) to the TCNQ acceptor (A). The TTF and TCNQ molecules adopt a mixed‐stack D⋅⋅⋅D⋅⋅⋅A arrangement that does not facilitate conduction. A solution EPR spectrum of 4 comprises a broad featureless singlet, which is consistent with the presence of a TCNQ radical anion. Theoretical studies were performed to probe the exchange interactions within selected fragments of 4 with and without charge transfer. In the absence of charge transfer, DFT calculations reveal weak antiferromagnetic exchange between verdazyl radicals within the ( 3 ) 2 monoradical unit. However, partial oxidation of the dimer ( 3 ) 2 to the diradical cation leads to an S = ground state, in which the verdazyl radical spins are now aligned co‐parallel as a consequence of antiferromagnetic exchange to the additional delocalised TTF‐based spin containing unit. The magnetic properties of 4 are consistent with a net S = spin state per formula unit with dominant antiferromagnetic interactions between spin‐bearing building blocks.
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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".