Design of Sterically Demanding, Electron-Rich Carbene Ligands with the Perimidine Scaffold
Bibliographic record
Abstract
A family of N, N ‘-disubstituted perimidinium cation salts were employed as precursors to persistent monomeric carbenes with novel molecular architectures and electronic structures. Depending on the substituents, reaction of these 1,3-disubstituted perimidinium cations with LiN(SiMe 3 ) 2 led either to deprotonation and generation of new carbenes or to enetetramines. In addition to spectroscopic characterization, crystallographic analysis of C 10 H 6 ( i PrN) 2 C ( 10 ), C 10 H 6 ( i PrN)(Me 3 CCH 2 N)C ( 11 ), {C 10 H 6 [N(3,5-Me 2 C 6 H 3 )] 2 C} 2 ( 13 ), and C 10 H 6 ( i PrN)(3,5-Me 2 C 6 H 3 N)C ( 14 ) definitively confirmed the nature of these species. The mixed benzyl/cycloheptyl-substituted carbene C 10 H 6 ( cyclo- C 7 H 13 N)(p-MeC 6 H 4 CH 2 N)C ( 17 ) was observed to undergo dimerization upon heating to yield both cis and trans isomers of the enetetramine {C 10 H 6 ( cyclo- C 7 H 13 N)( p- MeC 6 H 4 CH 2 N)C} 2, (17) 2 . Rhodium complexes of these perimidine-based carbenes were accessed via reactions with either monomeric carbene or enetetramine. Spectroscopic and crystallographic analysis of these rhodium−carbene complexes revealed the sterically demanding nature of the carbene ligands, which is manifested in the observation of hindered Rh−C carbene bond rotation and through % V bur measurements, and their exceptional electron-donating ability.
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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 | 0.001 | 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".