Dihydridoamine and Hydridoamido Complexes of Ruthenium(II) with a Tetradentate P−N−N−P Donor Ligand
Bibliographic record
Abstract
The new diphosphinediimine ligand PPh 2 C 6 H 4 CH NCMe 2 CMe 2 N CHC 6 H 4 PPh 2 {tmeP 2 N 2 } is prepared by reacting NH 2 CMe 2 CMe 2 NH 2 with 2 equiv of PPh 2 (C 6 H 4 -2-CHO). The diamine derivative PPh 2 C 6 H 4 CH 2 NHCMe 2 CMe 2 NHCH 2 C 6 H 4 PPh 2 {tmeP 2 (NH) 2 } is prepared by reducing tmeP 2 N 2 with LiAlH 4 . The reaction of RuHCl(PPh 3 ) 3 with tmeP 2 N 2 in THF produces the complex trans -RuHCl{tmeP 2 N 2 }, while a similar reaction of RuHCl(PPh 3 ) 3 with tmeP 2 (NH) 2 gives the complex trans -RuHCl{tmeP 2 (NH) 2 }, as a mixture of two isomers. The isomer with two N−H bonds syn to the Ru−H bond is converted on heating to an isomer thought to have one N−H syn to the Ru−H. The reaction of the two isomers with KO t Bu under Ar in toluene produces the novel hydridoamido complex RuH{tmeP 2 NNH}, where the ligand is deprotonated at one nitrogen. Reaction of this amido complex with H 2 gives exclusively the dihydridoamine complex trans -Ru(H) 2 {tmeP 2 (NH) 2 }. The complexes have been characterized by X-ray crystallography, NMR, IR, elemental analysis, and a deuterium exchange study. Complex RuH{tmeP 2 NNH}, or a combination of RuHCl{tmeP 2 (NH) 2 } and KO t Bu, slowly catalyzes the hydrogenation of acetophenone (6 atm H 2, 20 °C, benzene or 2-propanol). The catalytic cycle is thought to be similar to that for the ketone hydrogenation precatalyst trans -RuHCl{(S,S)-cyP 2 (NH) 2 )}. However in the present work both of the proposed catalysts trans -RuH 2 {tmeP 2 (NH) 2 } and RuH{tmeP 2 NNH} have been completely characterized. The tmeP 2 (NH) 2 system, with hindering methyl groups, is less active than the cyP 2 (NH) 2 system with a trans -1,2-substituted cyclohexyl backbone. The variable configuration of the amine nitrogens that is observed for the tmeP 2 (NH) 2 complexes might also occur in the cyP 2 (NH) 2 systems and could explain the inconsistent selectivity of such catalysts. The diimine complex RuHCl{tmeP 2 N 2 } reacts with KO t Bu under H 2 to produce the dihydridodiamine complex trans -Ru(H) 2 {tmeP 2 (NH) 2 }, the catalyst for the hydrogenation of acetophenone.
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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 | 0.001 | 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".