Laser Flash Photolysis Studies of Some Dimethylgermylene Precursors
Bibliographic record
Abstract
The laser flash photolysis of dodecamethylcyclohexagermane ( 1 ) and dimethylphenyl(trimethylsilyl)germane ( 5 ), two known photochemical precursors to dimethylgermylene (GeMe 2 ), has been reinvestigated. Laser flash photolysis of 1 in hexane solution affords markedly different results than were reported in an earlier study of this compound in cyclohexane. The present study shows it to yield two primary transient products, one exhibiting λ max = 490 nm and lifetime τ ≤ 10 ns and a second that exhibits λ max = 470 nm and decays on the microsecond time scale with second-order kinetics, with the concomitant growth of absorptions centered at λ max = 370 nm due to tetramethyldigermene (Ge 2 Me 4 ). The spectrum and absolute rate constants for quenching of the 470 nm species by acetic acid, 2,3-dimethyl-1,3-butadiene (DMB), CCl 4, and oxygen in hexane, as well as the transient behavior observed in the presence of millimolar concentrations of THF, are all quite similar to those established recently for GeMe 2 using 1-germacyclopent-3-ene derivatives as precursors. Two different transient products dominate the time-resolved spectra obtained from laser flash photolysis of 5 under similar conditions, one exhibiting λ max = 300 nm and τ ≈ 20 μs and a second exhibiting λ max = 430 nm and τ ≈ 4 μs. The latter species was assigned to GeMe 2 in earlier studies; it is re-assigned in the present work to the conjugated germene ( 6 ) derived from 1,3-trimethylsilyl migration into the ortho-position of the phenyl ring in 5, on the basis of comparisons of the spectrum and absolute rate constants for quenching of the species by oxygen, DMB, CCl 4, acetic acid, and acetone to those reported previously for the homologous silene derivative ( 11 ) and the corresponding 1,1-diphenyl-substituted analogues of the germene ( 12 ) and the silene ( 13 ). Weak transient absorptions consistent with the postpulse formation of Ge 2 Me 4 are also detectable from 5 in deoxygenated hexanes, but GeMe 2 itself cannot be detected.
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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 | 0.000 |
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".