<i>cis</i>, <i>trans</i> – or Both: Steric Bulk Determines Coordination Mode of Dimeric Palladium Complexes with Bridging Pyridine‐Phosphane Ligands
Bibliographic record
Abstract
Abstract The coordination mode in a metal complex is critically dependent on the ligands surrounding the metal, on the precursors used, and on the conditions during synthesis. Our goal was to obtain palladium compounds with pyridine‐phosphane ligands for catalysis. Therefore, we synthesized ligands 1a–d, which differ in the bulky aryl substituent at the pyridyl moiety. The palladium complexes 6a–d of these ligands are insoluble and have been characterized by various techniques, including solid‐state NMR and (for 6a, b, and d) single‐crystal X‐ray diffraction, showing that bimetallic complexes are formed in which two ligands span two palladium centers. The configuration around these centers is determined by the steric bulk of the ligand. In complexes 6c,d, with the ligands bearing the largest steric groups, both centers have a trans configuration of the methyl and chloride anions. With intermediately sized pyridyl substituents, complex 6b is formed, having one cis surrounded and one trans‐surrounded palladium center in the molecule. This kind of complexation has not been observed before. With the least bulky ligand, complex 6a is formed. Depending on the synthetic conditions employed, the methyl and the chloride in this complex can be in a cis configuration at both palladium atoms, or show the unique cis‐trans coordination.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
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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".