<sup>35</sup>Cl Solid-State NMR and Computational Study of Chlorine Halogen Bond Donors in Single-Component Crystalline Chloronitriles
Bibliographic record
Abstract
Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ-hole) and an electron donor, which has gained popularity in the field of crystal engineering due to its strength and linearity. Here, we present a 35 Cl solid-state NMR study of chlorine atoms as halogen bond donors, with interpretation aided by crystallographic symmetry and computational chemistry. In a series of chlorinated benzonitrile compounds, the magnitude of the 35 Cl quadrupolar coupling constant ( C Q ) was found to increase, and the quadrupolar asymmetry parameter (η) was found to decrease upon halogen bonding. A natural localized molecular orbital (NLMO) analysis attributes these changes to an increase in the contribution from the lone pair NLMOs to | C Q |. This is distinguished from a short proton-chlorine contact, which causes an increase in the magnitude of the σ-bond contribution and a decrease in the lone pair contribution, resulting in an overall decrease in | C Q |. This first direct 35 Cl solid-state NMR study of chlorine as a halogen bond donor provides new physical insight into the relationship between NMR observables and the halogen bond.
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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 | 0.001 | 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".