CP/MAS NMR and X-ray crystallographic characterization of <i>trans</i>-PdX<sub>2</sub>(PPh<sub>2</sub>vinyl)<sub>2</sub> (X = Cl, I); UV and Et<sub>2</sub>O·BF<sub>3</sub> reaction studies, including the formation of [Pd(µ-Cl)(PPh<sub>2</sub>vinyl)<sub>2</sub>]<sub>2</sub>[BF<sub>4</sub>]<sub>2</sub>
Bibliographic record
Abstract
The complexes PdCl2(PPh2vinyl)2 and PdI2(PPh2vinyl)2 have been prepared and crystallographically characterized as their trans square planar isomers. Trans-PdCl2(PPh2vinyl)2 exists in a centrosymmetric structure with a planar PdCl2P2 core whereas trans-PdI2(PPh2vinyl)2 shows no local Pd-centred symmetry and significant distortion of the PdI2P2 core from planarity. Crystallographic data is in accord with the 31P{1H} CP/MAS NMR spectra of the two complexes, which display a single resonance for the chloro-complex and two resonances for the iodo-complex. UV irradiation of CH2Cl2 solutions of PdCl2(PPh2vinyl)2 followed by re-dissolution in CDCl3 indicates no permanent chemical change. However, post-irradiation CP/MAS 31P{1H} NMR spectroscopy demonstrates the presence of trans-PdCl2(PPh2vinyl)2 in two solid state structures, plus cis-PdCl2(PPh2vinyl)2. PdI2(PPh2vinyl)2 exists only in its trans form in both solid state and solution. Irradiation results in phosphine displacement and the formation of sym-[PdI2(PPh2vinyl)]2 and free phosphine, the latter being characterized as Ph2P(O)vinyl following aerobic oxidation. PdCl2(PPh2vinyl)2 reacts in the presence of Et2O·BF3 to afford [Pd(µ-Cl)(PPh2vinyl)2]2[BF4]2 whereas PdI2(PPh2vinyl)2 is recovered in 95% yield, with the remaining material undergoing phosphine abstraction to form sym-[PdI2(PPh2vinyl)]2.Key words: palladium, phosphine, alkene, isomerization, CP/MAS.
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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) | 0.003 | 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".