1,3,5-Tri(iodoethynyl)-2,4,6-trifluorobenzene: halogen-bonded frameworks and NMR spectroscopic analysis
Bibliographic record
Abstract
Halogen bonding is the non-covalent interaction between the region of positive electrostatic potential associated with a covalently bonded halogen atom, named the σ-hole, and a Lewis base. Single-crystal X-ray diffraction structures are reported for a series of seven halogen-bonded cocrystals featuring 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene (1) as the halogen-bond donor, and bromide ions (as ammonium or phosphonium salts) as the halogen-bond acceptors: (1)·MePh3PBr, (1)·EtPh3PBr, (1)·acetonyl-Ph3PBr, (1)·Ph4PBr, (1)·[bis(4-fluorophenyl)methyl]triphenylphosphonium bromide, and two new polymorphs of (1)·Et3BuNBr. The cocrystals all feature moderately strong iodine–bromide halogen bonds. The crystal structure of pure [bis(4-fluorophenyl)methyl]triphenylphosphonium bromide is also reported. The results of a crystal engineering strategy of varying the size of the counter-cation are explored, and the features of the resulting framework materials are discussed. Given the potential utility of (1) in future crystal engineering applications, detailed NMR analyses (in solution and in the solid state) of this halogen-bond donor are also presented. In solution, complex13C and19F multiplets are explained by considering the delicate interplay between variousJcouplings and subtle isotope shifts. In the solid state, the formation of (1)·Et3BuNBr is shown through significant13C chemical shift changes relative to pure solid 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene.
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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".