Gas-phase reactions of atomic lanthanide cations with methyl chloride Periodicities in reactivity
Bibliographic record
Abstract
Room temperature reactions of lanthanide atomic cations (excluding Pm+) with CH3Cl are surveyed systematically in the gas phase using an inductively coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. Reaction rate coefficients are reported along with product distributions in He at 0.35 Torr (1 Torr = 133.3224 Pa) and 295 K. Cl atom transfer is the predominant reaction channel observed with all 14 lanthanide cations, but minor CH3Cl addition also occurs with the late lanthanide cations Dy+, Ho+, Er+, Tm+, and Yb+. The reaction efficiency for Cl atom transfer is shown to be governed by the energy required to promote an electron to achieve a d1s1 excited electronic configuration in which two non-f electrons are available for bonding: it decreases as the promotion energy increases and the periodic trend in reaction efficiency along the lanthanide series matches the periodic trend in the corresponding electron-promotion energy. This behaviour is consistent with a CCl bond insertion mechanism of the type proposed previously for insertion reactions of Ln+ cations with hydrocarbons and methyl fluoride. Direct Cl atom abstraction by a harpoonlike mechanism was excluded because of an observed noncorrelation of reaction efficiency with IE(Ln+). A remarkable Arrhenius-like correlation is observed for the dependence of reactivity on promotion energy: the early and late lanthanide cations exhibit characteristic temperatures of (1.4 ± 0.2) × 104 and (4.5 ± 0.3) × 103 K, respectively. A rapid second Cl atom transfer occurs with LaCl+, CeCl+, GdCl+, TbCl+, and LuCl+, but there was no evidence for a third chlorine atom abstraction with any of the LnCl2+ cations. Both LnCl+ and LnCl2+ add up to five methyl chloride molecules under the experimental operating conditions of the ICP/SIFT tandem mass spectrometer.Key words: lanthanide cations, Cl atom transfer, electron promotion, methyl chloride.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".