Kinetics and mechanisms of the reactions of transient silylenes with amines
Bibliographic record
Abstract
The N–H insertion reactions of dimethyl‐, diphenyl‐, and dimesitylsilylene (SiMe2, SiPh2, and SiMes2, respectively) with n‐butylamine (BuNH2) and diethylamine (Et2NH) were studied in hexanes by steady‐state and laser photolysis methods. The process begins with the formation of the corresponding Lewis acid–base complexes, which decayed with second‐order kinetics at rates that show modest sensitivity to silylene and amine structures. The complexation process, which was also studied using triethylamine (Et3N), proceeds at rates close to the diffusion limit, but the rate constants vary systematically with steric bulk in the amine. Equilibrium constants were determined for the complexation of Et2NH and Et3N with SiMes2, which proceeds reversibly. The complexes of SiMe2 and SiPh2 with BuNH2 and Et2NH decayed with pseudo‐first‐order rate coefficients in the 104–105 s–1 range. This is consistent with upper limits of about 106 M–1 s–1 for the rate constants for amine‐catalyzed H‐migration, which is thought to be the dominant mechanism for product formation from the complexes. The results are compared to published kinetic data for the O–H insertion reactions of these silylenes with alcohols, which also proceeds via initial complexation followed by catalytic proton transfer. The results indicate that catalyzed H‐transfer in the amine complexes is at least 104 times slower than the analogous process in silylene–MeOH complexes. The experimental data are compared to the results of theoretical calculations of the SiMe2 + NH2Me and SiMe2 + MeOH potential energy surfaces, carried out at the Gaussian‐4 and B3LYP/6‐311 + G(d,p) levels of theory. Copyright © 2011 John Wiley & Sons, Ltd.
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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 | 0.001 |
| 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 | 0.001 |
| Open science | 0.000 | 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".