The First Ru(η<sup>3</sup>-PCP) Complexes of the Electron-Rich Pincer Ligand 1,3-Bis((dicyclohexylphosphino)methyl)benzene: Structure and Mechanism in Transfer Hydrogenation Catalysis
Bibliographic record
Abstract
Mild routes to the first Ru(η 3 -pincer) derivatives of bis((dicyclohexylphosphino)methyl)benzene are reported. RuCl(η 3 -PCP)(PPh 3 ) ( 3 ·PPh 3; PCP = [2,6-(Cy 2 PCH 2 ) 2 C 6 H 3 ]) is formed quantitatively on reaction of the PC(H)P-arene ligand with RuCl 2 (PPh 3 ) 3 at 22 °C in the presence of base. Treatment of 3 ·PPh 3 with KHB s Bu 3 under nitrogen atmosphere generates RuH(η 3 -PCP)(PPh 3 )(N 2 ), 4, as a mixture of conformational isomers in which the hydride and N 2 ligands are trans or cis ( 4a or 4b, respectively). On exposure to H 2, 4a/b undergo immediate, quantitative exchange of bound N 2 for η 2 -H 2, affording the corresponding isomers of RuH(η 3 -PCP)(PPh 3 )(H 2 ), 5a/b . Complex 3 ·PPh 3 resists displacement of PPh 3 by H 2 at 22 °C, but on exposure to CO, readily yields RuCl(η 3 -PCP)(CO) 2, 6 . Transfer hydrogenation of ketones is efficiently catalyzed by 3 ·PPh 3 and 4, in a pathway involving loss of PPh 3 and (for 3 ) exchange of chloride for hydride. The duration of pretreatment of 3 ·PPh 3 with base (KOH, t BuOK) in refluxing 2-propanol is critical to activity, and indirect evidence supports formation of a catalytically active dihydride species during this process. X-ray crystal structures are reported for 3, 4a, 5a, and 6 .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".