Cationic Phosphinidene as a Versatile P<sub>1</sub> Building Block: [L<sub>C</sub>–P]<sup>+</sup> Transfer from Phosphonio–Phosphanides [L<sub>C</sub>–P–PR<sub>3</sub>]<sup>+</sup> and Subsequent L<sub>C</sub> Replacement Reactions (L<sub>C</sub> = N-Heterocyclic Carbene)
Bibliographic record
Abstract
Cationic imidazoliumyl(phosphonio)-phosphanides [L C –P–PR 3 ] + ( 1a–e +, L C = 4,5-dimethyl-1,3-diisopropylimidazolium-2-yl; R = alkyl, aryl) are obtained via the nucleophilic fragmentation of tetracationic tetraphosphetane [(L C –P) 4 ][OTf] 4 ( 2 [OTf] 4 ) with tertiary phosphanes. They act as [L C –P] + transfer reagents in phospha-Wittig-type reactions, when converted with various thiocarbonyls, giving unprecedented cationic phosphaalkenes [L C –P═CR 2 ] + ( 5a-f [OTf]) or phosphanides [L C –P–CR(NR 2 ′ )] + ( 6a-d [OTf]). Theoretical calculations suggest that three-membered cyclic thiophosphiranes are crucial intermediates of this reaction. To test this hypothesis, treatment of [L C –P–PPh 3 ] + with phosphaalkenes, that are isolobal to thioketones, permits the isolation of diphosphirane salts 11a,b [OTf]. Furthermore, preliminary studies suggest that the cationic phosphaalkene [L C –P═CPh 2 ] + may be employed to access rare examples of η 2 –P═C π-complexes with Pd 0 and Pt 0 when treated with [Pd(PPh 3 ) 4 ] and [Pt(PPh 3 ) 3 ] for which analogous complexes of neutral phosphaalkenes are scarce. The versatility of [L C –P] + as a valuable P 1 building block was showcased in substitution reactions of the transferred L C -substituent using nucleophiles. This is demonstrated through the reactions of 5a [OTf] and 6c [OTf] with Grignard reagents and KNPh 2, providing a convenient, high-yielding access to MesP═CPh 2 ( 16 ) and otherwise difficult-to-synthesize 1,3-diphosphetane 17 and P-aminophosphaalkenes.
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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".