Solid-State NMR Spectroscopic Study of Coordination Compounds of XeF<sub>2</sub> with Metal Cations and the Crystal Structure of [Ba(XeF<sub>2</sub>)<sub>5</sub>][AsF<sub>6</sub>]<sub>2</sub>
Bibliographic record
Abstract
The coordination compounds [Mg(XeF(2))(2)][AsF(6)](2), [Mg(XeF(2))(4)][AsF(6)](2), [Ca(XeF(2))(2.5)][AsF(6)](2), [Ba(XeF(2))(3)][AsF(6)](2), and [Ba(XeF(2))(5)][AsF(60](2) were characterized by solid-state (19)F and (129)Xe magic-angle spinning NMR spectroscopy. The (19)F and (129)Xe NMR data of [Mg(XeF(2))(2)][AsF(6)](2), [Mg(XeF(2)(4)][AsF(6)](2), and [Ca(XeF(2))(2.5)][AsF(6)](2) were correlated with the previously determined crystal structures. The isotropic (19)F chemical shifts and (1)J((129)Xe-(19)F) coupling constants were used to distinguish the terminal and bridging coordination modes of XeF(2). Chemical-shift and coupling-constant calculations for [Mg(XeF(2))(4)][AsF(6)](2) confirmed the assignment of terminal and bridging chemical-shift and coupling-constant ranges. The NMR spectroscopic data of [Ba(XeF(2))(3)][AsF(6)](2) and [Ba(XeF(2))(5)][AsF(6)](2) indicate the absence of any terminal XeF(2) ligands, which was verified for [Ba(XeF(2))(5)][AsF(6)](2) by its X-ray crystal structure. The adduct [Ba(XeF(2))(5)][AsF(6)](2) crystallizes in the space group Fmmm, with a = 11.6604(14) Angstrom, b = 13.658(2) Angstrom, c = 13.7802(17) Angstrom, V = 2194.5(5) Angstrom(3) at -73 degrees C, Z = 4, and R = 0.0350 and contains two crystallographically independent bridging XeF(2) molecules and one nonligating XeF(2) molecule. The AsF(6-) anions in [Mg(XeF(2))(4)][AsF(6)](2), [Ca(XeF(2))(2.5)][AsF(6)](2), [Ba(XeF(2))(3)][AsF(6)](2), and [Ba(XeF(2))(5)][AsF(6)](2) were shown to be fluxional with the fluorines-on-arsenic being equivalent on the NMR time scale, emulating perfectly octahedral anion symmetry.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".