Gas-Phase Reactions of Transition-Metal Ions with Molecular Oxygen: Room-Temperature Kinetics and Periodicities in Reactivity
Bibliographic record
Abstract
An Inductively-Coupled Plasma/Selected-Ion Flow Tube (ICP/SIFT) tandem mass spectrometer has been employed in a systematic survey of room- temperature reactions of O 2 with 29 transition-metal ions. The atomic ions are produced at ca. 5500 K in an ICP source and are allowed to decay radiatively and to thermalize by collisions with Ar and He atoms prior to reaction. Rate coefficients were measured for the reactions of first-row atomic ions from Sc + to Zn +, of second-row atomic ions from Y + to Cd + (excluding Tc + ) and of third-row atomic ions from La + to Hg + . Both O-atom abstraction and O 2 addition were observed as primary reaction channels. Periodicities in reactivity are identified and are compared with periodicities in the O-atom affinity of the atomic ion. O-atom abstraction was observed to be efficient when exothermic and inefficient when endothermic. NbO +, MoO +, TaO +, and WO + reacted further in a second O-atom transfer reaction with O 2 . ReO 2 + produced by direct addition of O 2 to Re + reacted further by both O-atom abstraction and O 2 addition. Sequential O 2 addition was observed to produce the higher oxides: MO 3 + (M = Ti, V, Y, Zr, Hf, Os), MO 4 + (M = Cr, Fe, Co, Ni, Cu, Nb, Mo, Ru, Rh, Hf, Ta, W, Re, Os, Ir, Pt, Au), MO 5 + (M = V, Re, Os), MO 6 + (M = Nb, W, Re) and MO 7 + (M = V). Novel termolecular reactions second-order in oxygen were identified for Os + and ZrO + at high oxygen concentrations to produce O 2 + and OsO + from Os + and a neutral metal oxide from Zr + .
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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) | 0.001 | 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".