Reversible Redox, Spin Crossover, and Superexchange Coupling in 3<i>d</i> Transition‐Metal Complexes of <i>Bis</i>‐azinyl Analogues of 2,2′:6′,2′′‐Terpyridine
Bibliographic record
Abstract
The terpyridine‐inspired tridentate ligand, 2,6‐bis(5,6‐dialkyl‐1,2,4‐triazin‐3‐yl)‐pyridine (BTP), was synthesized and utilized to isolate five [M II (BTP) 2 ] 2+ (M = Fe and Co) transition‐metal complexes of various anions (BF 4 – , ClO 4 – , and NCS – ). Notably, when metal‐halide precursors are employed, 1:1 M/L products [Co 2 II (µ‐X) 2 (BTP) 2 X 2 ] (X = Cl or Br) are obtained, exhibiting µ‐halide bridges. All complexes were structurally characterized through single‐crystal X‐ray diffraction and their electrochemical and magnetic properties were investigated. Electrochemical studies reveal that the free BTP ligand has a single irreversible reduction, however; upon coordination to a metal center, stabilization of the reduced BTP ligand occurs and up to four reductive processes associated with the molecule are observed within the solvent window. The metal‐centered redox processes were either reversible or partially reversible, and fall within the range of 0.13 < E 1/2 < 0.90 V vs. Fc/Fc + . Although there was minimal effect on the redox properties of the metal centers, there is strong dependence on the spin state. SQUID magnetometry elucidated a low spin state for the Fe II complexes at room temperature, revealing a diamagnetic electronic structure. On the other hand, the cobalt monometallic complexes, [Co II (BTP) 2 ] 2+ , showed gradual spin crossover properties between 1.8–370 K, displaying a minor dependence on the spin crossover behavior based on the respective anion. Additionally, ferromagnetic exchange interactions of J = +2.57 and +2.98 cm –1 were obtained using the –2 J formalism for the dinuclear Co II complexes, [Co 2 II (µ‐X) 2 (BTP) 2 X 2 ] for X = Cl and Br, respectively.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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 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".