Hydroboration of Carbon Dioxide Using Ambiphilic Phosphine–Borane Catalysts: On the Role of the Formaldehyde Adduct
Bibliographic record
Abstract
Ambiphilic phosphine–borane derivatives 1-B(OR) 2 -2-PR′ 2 –C 6 H 4 (R′ = Ph ( 1 ), i Pr ( 2 ); (OR) 2 = (OMe) 2 ( 1a, 2a ); catechol ( 1b, 2b ) pinacol ( 1c, 2c ), −OCH 2 C(CH 3 ) 2 CH 2 O– ( 1d )) were tested as catalysts for the hydroboration of CO 2 using HBcat or BH 3 ·SMe 2 to generate methoxyboranes. It was shown that the most active species were the catechol derivatives 1b and 2b . In the presence of HBcat, without CO 2, ambiphilic species 1a, 1c, and 1d were shown to transform to 1b, whereas 2a and 2c were shown to transform to 2b . The formaldehyde adducts 1b·CH 2 O and 2b·CH 2 O are postulated to be the active catalysts in the reduction of CO 2 rather than being simple resting states. Isotope labeling experiments and density functional theory (DFT) studies show that once the formaldehyde adduct is generated, the CH 2 O moiety remains on the ambiphilic system through catalysis. Species 2b·CH 2 O was shown to exhibit turnover frequencies for the CO 2 reduction using BH 3 ·SMe 2 up to 228 h –1 at ambient temperature and up to 873 h –1 at 70 °C, mirroring the catalytic activity of 1b .
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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) | 0.001 | 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".