Structures and Unimolecular Reactivity of Gas-Phase [Zn(Proline-H)]<sup>+</sup> and [Zn(Proline-H)(H<sub>2</sub>O)]<sup>+</sup>
Bibliographic record
Abstract
A combination of IRMPD spectroscopy, collision-induced dissociation, deuterium isotopic substitution, and computational chemistry was used to determine the structure and unimolecular chemistry of [Zn(Pro-H)](+) and the singly hydrated complex in the gas phase. Five competing dissociation channels were observed: loss of H2O, CO, CO2, and HCOOH and the main fragmentation pathway, loss of neutral Zn. By comparing the IRMPD spectrum with the predicted IR spectra of the lowest energy structures, it was confirmed that [Zn(Pro-H)](+) complex is deprotonated at the amine moiety, and a hydrogen from either C2 or C5 migrated to Zn(2+). In this H-type complex, ZnH(+) was chelated between the amine nitrogen and the carbonyl oxygen. Calculations of the potential energy surface revealed that the loss of neutral zinc is energetically more favorable than the loss of dehydrogenated proline leading to ZnH(+) product. Furthermore, calculations on all five primary decomposition routes, all beginning with the lowest energy structure, revealed that loss of Zn has the lowest energy requirement, consistent with it being the most abundant product of unimolecular dissociation following collisional or IR multiphoton activation. For the singly hydrated complex, [Zn(Pro-H)(H2O)](+), IRMPD spectroscopy confirms a structure with water added to the H-type structure and intramolecularly hydrogen bonded to the deprotonated amine site. This structure is not the lowest-energy [Zn(Pro-H)(H2O)](+) isomer, but it is the one where water is added to the lowest energy [Zn(Pro-H)](+) isomer.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| 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 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".