Dynamic Disorder and Electronic Structures of Electron-Precise Dianionic Diboranes: Insights from Solid-State Multinuclear Magnetic Resonance Spectroscopy
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide The J ( 11 B, 11 B) coupling constants of various salts of the electron-precise hexacyanodiborane(6) dianion, [B 2 (CN) 6 ] 2–, were obtained using 11 B double-quantum-filtered (DQF) J -resolved solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Our results show that the magnitude of the DQF J splitting is influenced by both the crystallographic symmetry of the system and the presence of dynamics. The splittings are amplified by a factor of 3 as compared to the corresponding theoretical J coupling constants for cases where (1) there is an absence of dynamics but the boron pairs are crystallographically equivalent or (2) the boron pairs are crystallographically inequivalent but are rendered magnetically equivalent on the time scale of the experiment due to dynamic disorder, which was identified by 11 B and 13 C SSNMR experiments. Consequently, molecular motions need to be taken into consideration when interpreting the results of DQF J -resolved experiments, and conversely, these experiments may be used to identify dynamic disorder. Variable-temperature NMR data support the notion of three different motional processes with correlation times ranging from 10 2 to 10 6 s –1 over the temperature range of 248–306 K. When molecular motion and crystallographic symmetry are both accounted for, the J ( 11 B, 11 B) coupling constants for various [B 2 (CN) 6 ] 2– salts were measured to range from 29.4 to 35.8 Hz, and their electronic origins were determined using natural localized molecular orbital and natural bond orbital analyses. The coupling constants were found to strongly correlate to the hybridization states of the boron orbitals that form the B–B bonds and to the strength of the B–B bonds. This study provides a novel tool to study dynamics in ordered and disordered solids and provides new perspectives on electron-precise dianionic diboranes featuring two-center–two-electron bonds in the context of related compounds featuring multiply and singly bonded boron spin pairs.
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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) | 0.000 | 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 | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".