Rethinking the Lewis Acidity of Cationic Gallium and Indium Catalysts
Bibliographic record
Abstract
Indium compounds are commonly considered weaker Lewis acids than their gallium counterparts. We explore the difference in Lewis acidity of the cationic dialkylgallium [GaR 2 (THF) 2 ] + and indium [InR 2 (THF) n ] + species and show that the gallium compounds are more active for the cationic polymerization of epoxide and ε-caprolactone. We rationalize this difference in reactivity by quantifying the relative Lewis acidity of the gallium and indium complexes. Experimental probes such as the Gutmann–Beckett and the fluorescent Lewis adduct method show that the gallium complexes are somewhat more Lewis acidic than the indium analogues, but not sufficiently to explain the major difference in reactivity. Computational studies suggest that, in solution, indium complexes exist in an equilibrium between [InR 2 (THF) 2 ] + and [InR 2 (THF) 3 ] + while the gallium species are stable as [GaR 2 (THF) 2 ] + . Global Electrophilicity Index calculations for all possible THF coordinate compounds of alkylgallium and alkylindium show that indium species are consistently more Lewis acidic than their gallium counterparts with the same number of coordinated THF molecules. We propose that the slow reactivity of indium species is not due to weaker Lewis acidity but rather is due to their ability to accommodate additional donor substrates.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| 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) | 0.000 | 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 teacher head, 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".