Comparison of Structure and Reactivity of Phosphine-Amido and Hemilabile Phosphine-Amine Chelates of Rhodium
Bibliographic record
Abstract
A series of mono- and binuclear rhodium(I) complexes bearing ortho-phosphinoanilido and ortho-phosphinoaniline ligands has been synthesized. Reactions of the protic monophosphinoanilines, Ph(2)PAr or PhPAr(2) (Ar = o-C(6)H(4)NHMe), with 0.5 equiv of [Rh(μ-OMe)(COD)](2) result in the formation of the neutral amido complexes, [Rh(COD)(P,N-Ph(2)PAr(-))] or [Rh(COD)(P,N-PhP(Ar(-))Ar)] (Ar(-) = o-C(6)H(4)NMe(-)), respectively, through stoichiometrically controlled deprotonation of an amine by the internal methoxide ion. Similarly, the binuclear complex, [Rh(2)(COD)(2)(μ-P,N,P',N'-mapm(2-))] (mapm(2-) = Ar(Ar(-))PCH(2)P(Ar(-))Ar), can be prepared by reaction of the protic diphosphinoaniline, mapm (Ar(2)PCH(2)PAr(2)), with 1 equiv of [Rh(μ-OMe)(COD)](2). An analogous series of hemilabile phosphine-amine compounds can be generated by reactions of monophosphinoanilines, Ph(2)PAr' or PhPAr'(2) (Ar' = o-C(6)H(4)NMe(2)), with 1 equiv of [Rh(NBD)(2)][BF(4)] to generate [Rh(NBD)(P,N-Ph(2)PAr')][BF(4)] or [Rh(NBD)(P,N-PhPAr'(2))][BF(4)], respectively, or by reactions of diphosphinoanilines, mapm or dmapm (Ar'(2)PCH(2)PAr'(2)), with 2 equiv of the rhodium precursor to generate [Rh(2)(NBD)(2)(μ-P,N,P',N'-mapm)][BF(4)](2) or [Rh(2)(NBD)(2)(μ-P,N,P',N'-dmapm)][BF(4)](2), respectively. Displacement of the diolefin from [Rh(COD)(P,N-Ph(2)PAr(-))] by 1,2-bis(diphenylphosphino)ethane (dppe) yields [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] which, while unreactive to H(2), reacts readily and irreversibly with oxygen to form the peroxo complex, [RhO(2)(P,P'-dppe)(P,N-Ph(2)PAr(-))], and with iodomethane to yield [RhI(CH(3))(P,P'-dppe)(P,N-Ph(2)PAr(-))]. Hemilabile phosphine-amine compounds can also be prepared by reactions of [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] with Me(3)OBF(4) or HBF(4)·Et(2)O, resulting in (thermodynamic) additions at nitrogen to form [Rh(P,P'-dppe)(P,N-Ph(2)PAr')][BF(4)] or [Rh(P,P'-dppe)(P,N-Ph(2)PAr)][BF(4)], respectively. The nonlabile phosphine-amido and hemilabile phosphine-amine complexes were tested as catalysts for the silylation of styrene. The amido species do not require the use of solvents in reaction media, can be easily removed from product mixtures by protonation, and appear to be more active than their hemilabile, cationic congeners. Reactions catalyzed by either amido or amine complexes favor dehydrogenative silylation in the presence of excess olefin, showing modest selectivities for a single vinylsilane product. The binuclear complexes, which were prepared in an effort to explore possible catalytic enhancements of reactivity due to metal-metal cooperativity, are in fact somewhat less active than mononuclear species, discounting this possibility.
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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) | 0.001 | 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 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".