Solvation of Yttrium with Ammonia: An Experimental and Theoretical Study
Bibliographic record
Abstract
The reactivity of the yttrium atom toward ammonia at room temperature has been investigated in a fast-flow reactor. The first step in the reaction is the rapid formation of yttrium imide (YNH) through the oxidative addition of the N−H bond of ammonia and the elimination of molecular hydrogen. The reaction continues with the solvation of yttrium imide with up to three molecules of ammonia. An equilibrium is established between the YNH(NH 3 ) 2 and YNH(NH 3 ) 3 species. The binding energy of NH 3 in the YNH(NH 3 ) 3 complex is found to be 19.7 ± 0.3 kcal/mol. Reaction rates have been determined for the solvation processes. Density functional calculations indicate that up to four ammonia molecules can bind to YNH at 0 K. The calculated D e is highest for the YNH−NH 3 complex and decreases abruptly following the addition of the third ammonia molecule. The calculated binding energy of the YNH(NH 3 ) 3 complex is 12 kcal/mol, in fair agreement with experiment. The YNH(NH 3 ) 4 complex is too weakly bound to be observed in our experiment. The structures of the complexes have been determined through full geometry optimizations. A molecular orbital analysis indicates that ammonia molecules are ligated to the positive end (Y) of the large dipole of YNH through dipole−dipole interactions and dative bond formation. The singly occupied sp hybrid on Y forces the ammonia molecules to bind side-on to Y.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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 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".