Experimental and Theoretical Investigations of the Contact Ion Pairs Formed by Reactions of the Anions [(EPR<sub>2</sub>)<sub>2</sub>N]<sup>−</sup> (R = <sup>i</sup>Pr, <sup>t</sup>Bu; E = S, Se) with the Cations [(TePR<sub>2</sub>)<sub>2</sub>N]<sup>+</sup> (R = <sup>i</sup>Pr, <sup>t</sup>Bu)
Bibliographic record
Abstract
Reactions of the sodium salts [(EPR(2))(2)N]Na(TMEDA) (R = (i)Pr, (t)Bu; E = S, Se) with the iodide salts [(TePR(2))(2)N]I (R = (i)Pr, (t)Bu) in toluene produce the mixed-chalcogen systems [(EPR(2))(2)N][(TePR(2))(2)N] (6b, E = Se, R = (t)Bu; 6c, E = S, R = (t)Bu; 7b, E = Se, R = (i)Pr; 7c, E = S, R = (i)Pr). Compounds 6b, 6c, 7b, and 7c have been characterized in solution by variable-temperature multinuclear ((31)P, (77)Se, and (125)Te) NMR spectroscopy and in the solid state by single-crystal X-ray crystallography. The structures are comprised of contact ion pairs linked by bonds between Te and S or Se atoms. For the tert-butyl derivatives 6b and 6c, the anionic half of the molecule is coordinated in a bidentate (E,E') fashion to one Te atom of the cationic half to give a spirocycle, whereas in the isopropyl derivatives 7b and 7c, the anion acts as a monodentate ligand with only one E-Te bond and the second S or Se atom pointing away from the cation. A comparison of the chalcogen-chalcogen bond orders in 6b, 6c, and the all-tellurium system 6a (E = Te), as determined from the experimental bond lengths, shows that the Te-Te bond order in the cations decreases as the strength of the E-Te interaction increases. This trend is attributed to increased electron donation from the anion into the lowest unoccupied molecular orbital [sigma*(Te-Te)] of the cation along the series S < Se < Te. A similar trend is observed for the monodentate contact ion pairs 7b and 7c. Density functional theory calculations provided information about the relative energies of bidentate and monodentate contact ion pair structures and the extent of intramolecular electron transfer in these systems.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".