A combined kinetic and computational study of the reactions of transient germylenes with oxiranes and thiiranes in solution
Bibliographic record
Abstract
The reactions of dimethyl- and diphenylgermylene (GeMe2 and GePh2, respectively) with cyclohexene oxide (CHO) and propylene sulfide (PrS) have been studied in hydrocarbon solvents at 25 °C by laser flash and steady-state photolysis methods using appropriately substituted germacyclopent-3-ene derivatives as germylene precursors. GeMe2 reacts with CHO and PrS with rate constants in the range of 1.2–1.7 × 1010 M−1 s−1 in hexanes at 25 °C to form new transient products that are assigned to the corresponding Lewis acid-base complexes of the germylene with the substrates. The complexation reactions were found to be reversible and are characterized by equilibrium constants of KC = (3.7 ± 0.8) × 103 M−1 and (3 ± 1) × 104 M−1 for complexation of GeMe2 with CHO and PrS, respectively. The complexes decay over approximately 10 μs with the concomitant formation of tetramethyldigermene (Ge2Me4), identifiable by its characteristic UV-vis spectrum centered at λmax = 370 nm. Diphenylgermylene behaves analogously, reacting rapidly and reversibly with the two substrates to form the corresponding Lewis acid-base complexes (λmax ≈ 355 nm) that decay over several tens of microseconds with the concomitant growth of the characteristic UV-vis spectrum of tetraphenyldigermene (Ge2Ph4) (λmax = 440 nm). Steady-state photolysis of the germylene precursors in the presence of CHO afforded germanium-containing oligomers but showed no evidence of oxygen abstraction or the formation of substrate-derived product(s). Similar photolyses in the presence of PrS also afforded germanium-containing oligomers, but as well yielded propene in 20%–30% yield and (in the case of the GePh2 precursor) minor amounts of low molecular weight compounds that appear to be derived from the corresponding germanethione. Density functional theory calculations of the chalcogen abstraction reactions of GeMe2 with oxirane and thiirane in the gas phase have been carried out at the B3LYP/6-311+G(d,p) level of theory and are in good qualitative agreement with the experimental data.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".