Solution and Solid-State Characteristics of Imine Adducts with Tris(pentafluorophenyl)borane
Bibliographic record
Abstract
Adducts of the N -benzyl imines Ph(R)C NBn (R = Ph, CH 3, H) and t Bu(CH 3 )C NBn and the N -phenyl imine Ph(H)C NPh with the Lewis acid tris(pentafluorophenyl)borane, B(C 6 F 5 ) 3, have been prepared and characterized in solution and in the solid state. For each imine, the Lewis acid is N-bound, with the exception of the sterically demanding base t Bu(CH 3 )C NBn, which reacts with B(C 6 F 5 ) 3 through its enamine tautomer to form an α-C bound adduct, 5 . In the N-bound imine−borane adducts 1 − 4, steric crowding and π-stacking between C 6 F 5 and C 6 H 5 rings results in restricted rotation about the B−N and B−C bonds; the dynamic behavior which results can be studied using variable-temperature 19 F and 1 H NMR spectroscopy. For the unsymmetrical ketimines and aldimines, kinetic adducts of the thermodynamically dominant free imine are observed to form initially upon treatment with B(C 6 F 5 ) 3; these adducts slowly convert thermally to the thermodynamic adducts of the less stable imine. For the ketimine Ph(CH 3 )C NBn, both the kinetic adduct 2-k and the thermodynamic adduct 2-t were fully characterized. In the solid-state structures of all the adducts except 5, one or two C 6 F 5 /C 6 H 5 stacking interactions are present; in one case, the adduct 3-t between B(C 6 F 5 ) 3 and Ph(H)C NBn, intermolecular stacking interactions are apparent in the crystal-packing diagram. The implications of the structures of these adducts for Lewis acid mediated addition of nucleophiles to imines is discussed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.009 | 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 teacher head, 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".