Probing the Effect of the Ligand X on the Properties and Catalytic Activity of the Complexes RuHX(diamine)(PPh<sub>3</sub>)<sub>2</sub> (X = OPh, 4-SC<sub>6</sub>H<sub>4</sub>OCH<sub>3</sub>, OPPh<sub>2</sub>, OP(OEt)<sub>2</sub>, CCPh, NCCHCN, CH(COOMe)<sub>2</sub>; diamine = 2,3-Diamino-2,3-dimethylbutane, (<i>R,R</i>)-1,2-Diaminocyclohexane)
Bibliographic record
Abstract
The reactivity of the ruthenium−amido bond in RuH(NH 2 CMe 2 CMe 2 NH)(PPh 3 ) 2 ( 1 ) toward weak acids HX and the influence of the X group on the catalytic activity of the resulting complex are explored here. Complex 1 reacts with the weak acids HX (X = OPh, 4-SC 6 H 4 OMe, OPPh 2, OP(OEt) 2, CCPh, NCCHCN, CH(COOMe) 2 ) to form complexes of the type RuHX(tmen)(PPh 3 ) 2 (tmen = 2,3-diamino-2,3-dimethylbutane). The complexes with X = PhOH···OPh, 4-SC 6 H 4 OMe, OP(OEt) 2, CCPh, CH(COOMe) 2 have been characterized by X-ray crystallography. The X group is situated trans to the hydride in all cases and is bonded to ruthenium via the donor atoms O, S, P, C, and O, respectively. The phenol in the phenoxide adduct RuH(PhOH···OPh)(tmen)(PPh 3 ) 2 bridges via hydrogen bonds between the alkoxide oxygen and an amino hydrogen to form a six-membered RuO···HO···HN ring. One carbonyl oxygen of the malonate bonds to the Ru, while the other accepts a hydrogen bond from an amino hydrogen. The analogous complexes RuHX(dach)(PPh 3 ) 2 (dach = ( R,R )-1,2-diaminocyclohexane) were synthesized by the reaction of RuHCl(dach)(PPh 3 ) 2 ( 2 ) with an equimolar amount of potassium tert -butoxide and HX. For all of the complexes the Ru−H vibrational frequency and the 1 H NMR chemical shift of Ru−H correlate with the electronegativity of the trans atom X. The amido complex 1 and the complexes with X = CH(COOMe) 2 and OPh are active catalysts for the Michael addition of dimethyl malonate to 2-cyclohexen-1-one. RuH(NCCHCN)(tmen)(PPh 3 ) 2 reacts with the Michael acceptor 2-cyclohexen-1-one to give RuH(NCC(C 6 H 9 O)CN)(tmen)(PPh 3 ) 2, a trapped Michael adduct that has been characterized by X-ray crystallography. On the basis of these observations a catalytic cycle for the Michael addition reactions is proposed that involves the addition of the C−H bond of the Michael donor to the Ru−N bond followed by attack on the Michael acceptor and elimination of the Michael adduct, possibly by a 1,3-proton migration as observed for the malononitrile adduct. Only the complexes with X = H, CCPh are catalysts or precatalysts for the hydrogenation of neat acetophenone to 1-phenylethanol in the absence of added base under 10 atm of H 2 at 20 °C. Evidence is provided that the phenylacetylide complexes are precatalysts that are converted to the active trans -dihydride catalysts (X = H).
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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 | 0.007 | 0.005 |
| Meta-epidemiology (narrow) | 0.008 | 0.006 |
| Meta-epidemiology (broad) | 0.008 | 0.005 |
| Bibliometrics | 0.003 | 0.013 |
| Science and technology studies | 0.005 | 0.007 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.008 | 0.005 |
| Research integrity | 0.004 | 0.007 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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; both teacher heads agree on what is shown here.
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".