Steric and Solvent Effects on the Secondary Kinetic α-Deuterium Isotope Effects in the Reaction of Methyl Iodide with Organoplatinum(II) Complexes: Application of a Second-Order Technique in Measuring the Rates of Rapid Processes
Bibliographic record
Abstract
The kinetic isotope effects (KIEs), k H / k D, have been determined for reaction of CH 3 I/CD 3 I with several organoplatinum(II) complexes [PtR 2 (NN)], in which the bidentate NN ligand is bpy = 2,2′-bipyridine, t Bu 2 bpy = 4,4′-bis( tert -butyl)-2,2′-bipyridine, phen = 1,10-phenanthroline, or Me 2 phen = 2,9-dimethyl-1,10-phenanthroline, at different temperatures and in solvents having different polarities. The values obtained for the secondary α-deuterium KIEs are close to 1 and are dependent on the solvent; values of up to 7−10% larger are obtained for the reactions in the polar solvent acetone as compared to those obtained in the nonpolar solvent benzene. The data also indicate that the steric crowding around the square-planar coordination sphere of the platinum(II) complexes with the ligand Me 2 phen results in higher KIEs. The reactions involving dimethylplatinum(II) complexes, [PtMe 2 (NN)], were fast, and a 1:1 molar ratio (of complex and reagent) technique was successfully used to measure the rate constants accurately by conventional UV−visible spectroscopy. It is shown that there are significant advantages to measuring the reaction rates under second-order condition, as compared to the usual pseudo-first-order method.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".