Chlorine, Bromine, and Iodine Solid-State NMR
Bibliographic record
Abstract
Chlorine-35, chlorine-37, bromine-79, bromine-81, and iodine-127 are all quadrupolar isotopes which are amenable to study by solid-state nuclear magnetic resonance (SSNMR) spectroscopy. In this contribution, we provide (i) an overview of the NMR properties of these isotopes; (ii) a discussion of the practical aspects of spectral acquisition for powdered samples, including particular challenges and advantages; (iii) details on data analysis and interpretation; (iv) an overview of representative quadrupolar coupling and chemical shift data; and (v) a discussion of various applications. The commercial availability of very high magnetic fields (e.g., B 0 ≥ 18.8 T) has increased the practicality of 35/37Cl, 79/81Br, and 127I SSNMR measurements because of the increased sensitivity afforded by high magnetic fields, as well as the reduction in second-order quadrupolar broadening of the central transition NMR lineshapes. These high magnetic fields have also rendered possible the measurement of quadrupolar halogen chemical shift tensors and the orientation of their principal axis systems with respect to the electric field gradient tensors. While the direct SSNMR observation of covalently bound halogens remains generally impractical (with the exception of symmetric perhalogenate ions), data for halides in noncubic environments have found application in the study of polymorphism, hydration state, structure, and local site symmetry in diverse systems including bioinorganic molecules, catalysts, glasses, materials, ionic liquids, and other small molecules.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| 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".