σ-Bonded Metal Carbonyl Cations and Their Derivatives: Syntheses and Structural, Spectroscopic, and Bonding Principles
Bibliographic record
Abstract
Homoleptic σ-bonded metal carbonyl cations (σ-carbonyls) and their derivatives have grown in recent years into a large subgroup of mononuclear metal carbonyl complexes. They are at present formed by 17 elements, including the post transition metal mercury. Most are generated in superacids: the Lewis superacid SbF 5 and the conjugate Brønsted−Lewis superacid HF−SbF 5 . Thermally stable salts are formed with the superacid anions [Sb 2 F 11 ] - and [SbF 6 ] - . Many of the cations are superelectrophilic, with metals in oxidation states of +2 or +3. Three different synthetic routes are developed: reductive (A) or solvolytic carbonylations (B) and oxidative methods (C). Considerable progress has been made by replacing the Lewis superacid SbF 5 as reaction medium by the conjugate Brønsted−Lewis superacid HF−SbF 5 . This allows reactions to proceed faster in a homogeneous phase and to produce crystalline materials. In total 27 mostly recent molecular structures have been obtained, including that of [Ir(CO) 6 ][SbF 6 ] 3 ·4HF, the first HF solvate with one of the HF molecules coordinated in an isotridentate mode to three carbon atoms of the cation. Due to the electrophilic nature of the carbonyl carbon in fluoroantimonate salts of metal carbonyl cations, extended structures are formed via significant interionic C- - - F contacts. A new σ-bonded carbonyl, (CF 3 ) 3 BCO, which has been fully characterized, expands the existence range of metal carbonyl cations to group 13. The large amount of spectroscopic and structural information accumulated is used to present a conceptually simple bonding model.
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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) | 0.002 | 0.001 |
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".