Kinetic study of the reaction of [Rh6(CO)16] with NO2−: insertion of the nitrogen atom into a Rh6 cluster core
Bibliographic record
Abstract
The cluster [Rh(6)(CO)(16)] reacts with (PPN)NO(2) [PPN = N(PPh(3))(2)] in dichloromethane to form the known cluster [Rh(6)N(CO)(15)](-) in which the nitrogen atom is encapsulated within a trigonal prismatic Rh(6) cluster. A kinetic study shows that the reactions proceed in six kinetically distinguishable steps followed by another four steps that are kinetically unidentifiable but that can nevertheless be identified speculatively on the basis of analogies to other reactions of carbonyl clusters. Stopped-flow studies show that the initial step involves bimolecular nucleophilic attack on a carbon atom of a CO ligand by an oxygen atom in the NO(2)(-) ion. This is followed by CO loss (via a [CO]-dependent and a [CO]-independent path) with formation of [Rh(6)(CO)(14)(OC[combining low line]ON[combining low line]O)](-). Activation parameters have been obtained for all three steps. [Rh(6)(CO)(14)(OC[combining low line]ON[combining low line]O)](-) has been characterized spectroscopically and has the C and N atoms coordinated to one Rh atom. Reaction of this cluster with CO leads to the fairly rapid establishment of an equilibrium with the adduct [Rh(6)(CO)(n)(OC[combining low line]ON[combining low line]O)](-), where n is most probably 15. Both participants in this equilibrium react more slowly with loss of CO(2), and these reactions show negligible dependence on temperature and are therefore largely entropy controlled. The overall reaction is very solvent dependent and numerous side reactions can be identified if the conditions of reaction are not closely controlled.
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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 | 0.001 | 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".