Chalcogen versus Dative Bonding in [SF<sub>3</sub>]<sup>+</sup> Lewis Acid–Base Adducts: [SF<sub>3</sub>(NCCH<sub>3</sub>)<sub>2</sub>]<sup>+</sup>, [SF<sub>3</sub>(NC<sub>5</sub>H<sub>5</sub>)<sub>2</sub>]<sup>+</sup>, and [SF<sub>3</sub>(phen)]<sup>+</sup> (phen = 1,10-phenanthroline)
Bibliographic record
Abstract
The Lewis-acid behavior of [SF 3 ][MF 6 ] (M = Sb, As) salts toward mono- and bidentate nitrogen bases was explored. Reactions of [SF 3 ][MF 6 ] with excesses of CH 3 CN and C 5 H 5 N yielded [SF 3 (L) 2 ] + (L = CH 3 CN, C 5 H 5 N) salts, whereas the reaction of [SF 3 ][SbF 6 ] with equimolar 1,10-phenanthroline (phen) in CH 3 CN afforded [SF 3 (phen)][SbF 6 ]·2CH 3 CN. Salts of these cations were characterized by low-temperature X-ray crystallography and Raman spectroscopy in the solid state as well as by 19 F NMR spectroscopy in solution. In the solid state, the geometries of [SF 3 (NC 5 H 5 ) 2 ] + and [SF 3 (phen)] + are square pyramids with negligible cation–anion contacts, whereas the coordination of CH 3 CN and [SbF 6 ] − to [SF 3 ] + in [SF 3 (NCCH 3 ) 2 ][SbF 6 ] results in a distorted octahedral coordination sphere with a minimal perturbation of the trigonal-pyramidal SF 3 moiety. 19 F NMR spectroscopy revealed that [SF 3 (L) 2 ] + is fluxional in excess L at −30 °C, whereas [SF 3 (phen)] + is rigid in CH 2 Cl 2 at −40 °C. Density functional theory (DFT-B3LYP) calculations suggest that the S–N bonds in [SF 3 (NC 5 H 5 ) 2 ] + and [SF 3 (phen)] + possess substantial covalent character and result in a regular AX 5 E VSEPR geometry, whereas those in [SF 3 (NCCH 3 ) 2 ] + are best described as S···N chalcogen-bonding interactions via σ-holes on [SF 3 ] +, which is consistent with the crystallographic data.
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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) | 0.003 | 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".