Competitive Activation of CH and CX Bonds in Reactions of Pt<sup>+</sup> with CH<sub>3</sub>X (X=F,Cl): Experiment and Theory
Bibliographic record
Abstract
The reactions of Pt(+) with CH(3)X (X=F, Cl) are studied experimentally by employing an inductively coupled plasma/selected-ion flow tube tandem mass spectrometer and theoretically by density functional theory. Dehydrogenation and HX elimination are found to be the primary reaction channels in the remarkably different ratios of 95:5 and 60:40 in the fast reactions of Pt(+) with CH(3)F and CH(3)Cl, respectively. The observed kinetics are consistent with quantum chemistry calculations, which indicate that both channels in the reaction with CH(3)F are exothermic with ground-state Pt(+)((2)D), but that HF elimination is prohibited kinetically because of a transition state that lies above the reactant entrance. The observed HF-elimination channel is attributed to a slow reaction of CH(3)F with excited-state Pt(+)((4)F) for which calculations predict a small barrier. The calculations also show that both the HCl-elimination and dehydrogenation channels observed with CH(3)Cl are thermodynamically and kinetically allowed, although the state-specific product distributions could not be ascertained experimentally. Further CH(3)F addition is observed with the primary products to produce PtCH(2) (+)(CH(3)F)(1,2) and PtCHF(+)(CH(3)F)(1,2). With CH(3)Cl, sequential HCl elimination is observed with PtCH(2) (+) to form PtC(n)H(2) (n) (+) with n=2, 3, which then add CH(3)Cl sequentially to form PtC(2)H(4) (+)(CH(3)Cl)(1-3) and PtC(3)H(6) (+)(CH(3)Cl)(1,2). Also, sequential addition is observed for PtCHCl(+) to form PtCHCl(+)(CH(3)Cl)(1,2).
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".