Trans Element-Hydrogen Bonds: A Distinctive Difference Between Transition Metals and Main Group Elements
Bibliographic record
Abstract
The change in sign of the interaction force constant between element-hydrogen stretching modes of trans-dihydrides of the d block and p block elements is analyzed for the first time. As the transition metal M approaches group 12, the higher energy symmetric trans-H–M–H vibration νsym approaches the energy of the antisymmetric vibration νasym. Crossing to group 13 elements E, the trans-H–E–H vibration νsym increasingly drops below νasym. This reversal is attributed to the d orbital that participates in the H–M–H bonding but is nonbonding in the H–E–H compounds. DFT calculations are used to probe the energetics of isoelectronic triatomic [H–M–H]n+ and [H–E–H]n− to reveal this trend and also to demonstrate that the magnitude of these interactions (νgap) increases down groups 11, 12, and 14 but remains fairly constant for group 13. They are also used to show that this reversal is seen in the transition state for hydride transfer to CO2 from the model compounds trans-NiH2(porphyrin) and trans-EH2(porphyrin), E = Si and Ge in their singlet states.
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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) | 0.000 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".