Electronic Effects in PCP-Pincer Ru(II)-Based Hydrogen Transfer Catalysis
Bibliographic record
Abstract
The synthesis and characterization of novel cyclometalated ruthenium(II) complexes [RuCl(PCP OMe )(PPh 3 )] and [RuCl(PCP CF3 )(PPh 3 )] containing monoanionic, tridentate coordinating PCP-pincer ligands [C 6 H 3 {CH 2 P( p -MeOC 6 H 4 ) 2 } 2 -2,6] - (PCP OMe ) and [C 6 H 3 {CH 2 P( p -CF 3 C 6 H 4 ) 2 } 2 -2,6] - (PCP CF3 ) are reported. These compounds have been tested as catalyst precursors in the hydrogen transfer reaction of cyclohexanone to cyclohexanol in 2-propanol using NaOH as a base. The initial rate of the hydrogen transfer reaction appeared to depend on the electronic character of the Ar 2 P− groups of the PCP-pincer ligand. Among the catalyst precursors studied, the complex [RuCl(PCP CF3 )(PPh 3 )] was found to exhibit the highest activity and the initial TOF exceeded that observed for the Ph 2 P analogue [RuCl(PCP Ph )(PPh 3 )]. Most importantly, catalysis performed with [RuCl(PCP CF3 )(PPh 3 )] does not require pretreatment of the precursor in the absence of substrate. Conversely, a different catalytic profile and a low activity were observed when either the electron-poor [RuCl{C 6 H 3 (CH 2 P(C 6 F 5 ) 2 ) 2 -2,6}(PPh 3 )] ([RuCl(PCP F20 )(PPh 3 )]) complex or its triflate analogue was used as catalyst precursors. NMR studies and ESI-MS measurements provided information concerning the catalytically active species formed during the pretreatment of the precursor complexes. The results indicate that during the pretreatment period a monoanionic, monohydride ruthenium(II) species, Na[Ru(H)(PCP i Pr )(O i Pr)(PPh 3 )], is selectively formed. The latter hydride complex was also obtained via an independent synthetic route. On the basis of both the present results and those previously reported in literature, a mechanism is proposed.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| 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) | 0.004 | 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".