Electronic and steric effects in fragmentation reactions of Os<sub>3</sub>(CO)<sub>9</sub>(μ-C<sub>4</sub>Ph<sub>4</sub>)
Bibliographic record
Abstract
P-Donor nucleophiles of cone angle >or=145 degrees are known to react with Os3(CO)9(mu-C4Ph4) quite differently from those with cone angles <or=143 degrees. A detailed and systematic kinetic study of the rather slow kinetics of reactions with 11 of the larger nucleophiles is described, and the results are analysed according to standard QALE protocols. (QALE=quantitative analysis of ligand effects). The results are compared with those previously reported for 17 of the smaller phosphines, which react much more rapidly. The pronounced difference in behaviour between these two groups of nucleophiles is ascribable to major differences between the ease of formation of different intermediate Os3(CO)9L(mu-C4Ph4) adducts. The cluster is proposed to be capable of opening up to form a nido structure that has a small, well defined opening capable of accommodating any of the smaller nucleophiles quite easily. However, this opened nido structure is concluded to be extremely rigid and incapable of further opening to accommodate any of the larger nucleophiles. These have to take advantage of an alternative nido structure that contains a much larger opening but that requires considerably more energy for it to be formed. These results are compared with those for the clusters M5C(CO)15(M=Ru or Fe), which show somewhat similar behaviour. This is ascribed to the complexity of the structures of the clusters that allows them to form alternative nido structures of the sort described, something that more symmetrical clusters are apparently incapable of doing.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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 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".