Solving the 170‐Year‐Old Mystery About Red‐Violet and Blue Transient Intermediates in the Gmelin Reaction
Why this work is in the frame
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Bibliographic record
Abstract
The Gmelin reaction between nitroprusside and sulfides in aqueous solution is known to produce two transient intermediates with distinct colors: an initial red-violet intermediate that subsequently converts into a blue intermediate. In this work, we use a combination of multinuclear ((17) O, (15) N, (13) C) NMR, UV/Vis, IR spectroscopic techniques and quantum chemical computation to show unequivocally that the red-violet intermediate is [Fe(CN)5 N(O)S](4-) and the blue intermediate is [Fe(CN)5 N(O)SS)](4-) . While the formation of [Fe(CN)5 N(O)S](4-) has long been postulated in the literature, this study provides the most direct proof of its structure. In contrast, [Fe(CN)5 N(O)SS)](4-) represents the first example of any metal coordination complex containing a perthionitro ligand. The new reaction pathways found in this study not only provide clues for the mode of action of nitroprusside for its pharmacological activity, but also have broader implications to the biological role of H2 S, potential reactions between H2 S and nitric oxide donor compounds, and the possible biological function of polysulfides.
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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 | 0.002 | 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 | 0.001 |
| 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