Direct Detection of Diphenylsilylene and Tetraphenyldisilene in Solution
Bibliographic record
Abstract
Photolysis of 1,1,3,3-tetramethyl-2,2-diphenyl-1,2,3-trisilacyclohexane ( 9 ) in hydrocarbon solvents affords diphenylsilylene (SiPh 2 ) and 1,1,2,2-tetramethyl-1,2-disilacyclopentane in nearly quantitative yields, as shown by the results of steady-state trapping experiments with methanol and acetone. SiPh 2 (λ max = 290, 515 nm) can be detected directly by laser flash photolysis of 9 in hexane, where it decays over 1−2 μs with the concomitant growth of a second transient species that is assigned to the dimer, tetraphenyldisilene (Si 2 Ph 4; λ max = 290, 370, 460 nm), on the basis of its spectrum and kinetic behavior. The transient spectroscopic behavior is similar to that observed in laser photolysis experiments with the dimethylsilylene (SiMe 2 ) and dimesitylsilylene (SiMes 2 ) precursors dodecamethylcyclohexasilane ( 1 ) and 2,2-dimesityl-1,1,1,3,3,3-hexamethyltrisilane ( 2 ), respectively, in the same solvent. Absolute rate constants for the reactions of the three silylenes with methanol and acetone have been measured under common conditions, providing the first quantitative glimpse of the electronic and steric effects of substituents on silylene reactivity in solution. The time-resolved spectroscopic behavior observed in laser photolysis experiments with 9 is also compared to those observed with the related, previously reported SiPh 2 precursors, 1,1,3,3-tetramethyl-2,2-diphenyl-1,2,3-trisilacycloheptane ( 6 ) and 1,1,1,3,3,3-hexamethyl-2,2-diphenyltrisilane ( 4 ), which are also briefly reinvestigated. The results show that the relatively weak absorptions due to SiPh 2 can in fact be detected from the latter compound, superimposed on the much more intense, long-lived transient absorptions due to the conjugated silene derivative that is known to be formed as a coproduct in the photolysis of this compound in solution at room temperature.
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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) | 0.001 | 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 | 0.001 |
| 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".