Microwave-Assisted Synthesis of Tricarbonyl Rhenacarboranes: Steric and Electronic Effects on the 1,2 → 1,7 Carborane Cage Isomerization
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Bibliographic record
Abstract
A series of tricarbonyl rhenacarboranes {[M][Re(CO)3(RR'C2B9H9)]} (M = Na, K) were synthesized in water using microwave radiation with reaction times of less than 15 min. The novel complexes were isolated in good yields (57-94%) as either 3,1,2-(R = H: R' = CH2Pyr 6; R' = CH2Cy, 20) or 2,1,8-(R = H: R' = H, 4; R' = CH2PyrMe 12; R' = CH2PyrH, 13; R' = Pyr, 15; R' = Ph, 17; R = R' = Bn, 19) metallacarboranes and characterized by multinuclear (1H, 11B, 13C) and NOE NMR spectroscopy, IR spectroscopy, mass spectrometry, and X-ray crystallography in the case of compounds 12 and 13. Carborane cage isomerization from the original 1,2 configuration to the 1,7 orientation occurred in cases where significant steric crowding was present at the metal center. Incorporation of a methylene spacer between the carborane cage and the six-membered ring as in 7 and 20 decreased steric strain such that the 3,1,2 configuration was maintained. Conversion of the 3,1,2 complex 6 to the 2,1,8 isomers 12 and 13 takes place at room temperature upon methylation or protonation of the pyridyl ring, indicating that electronic effects also play a significant role in the isomerization process.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 it