Bimetallic, Spirocyclic, Methylene-Bridged Carbene Complexes of Rhodium and Palladium Derived by Stepwise Metalations of Lithiated Bis(diphenylphosphoranotrimethylsilylimido)methandiide
Bibliographic record
Abstract
The Li−C−Rh, bimetallic, phosphinimine spirocyclic, bridged carbene complex 1 was readily prepared from dilithiobis(diphenylphosphoranosilylimido)methandiide, [ Li 2 L ] 2, and an equimolar (Rh/Li, 1:1) amount of [Rh(cod)Cl] 2 . Subsequent reaction with a different metal precursor, in the present cases, [Pd(allyl)Cl] 2, yielded the spirocyclic Rh−Pd heterobimetallic 2 or, if a second equivalent of [Rh(cod)Cl] 2 was used, the spirocyclic Rh−Rh homobimetallic 3 was obtained; thus the system presents an effective synthetic route for the preparation of homo- or heterobimetallic complexes. All of the complexes have constrained symmetry, which creates in some cases isomeric and enantiomeric structures. The Li−Rh complex 1 thermally rearranged to the chelated, orthometalated, Rh complex 6, wherein the Rh(I) center is bound to the ipso carbon of a phenyl ring and a methine carbon formed from protonation of the spiro carbon. Remarkably, controlled hydrolysis of 6 reversed the orthometalation and provided an iminophosphorane-methine chelate complex of Rh(I), 7 . Reactions of the cod-substituted complexes 2, 3, and 7 with CO resulted in the replacement of cod substituents to form parallel Rh carbonyl complexes ( 4, 5, and 8 ). The allyl substituents in the system were not affected. The carbonyl complexes 5 and 8 could be made independently from [Rh(CO) 2 Cl] 2 and either the dilithium methandiide or the methine form of the ligand as appropriate. Complexes 2 − 7 have been structurally characterized herein. Complexes 3 and 5 are chiral (because they lack rotation−reflection axes), but the products here are unresolved racemic mixtures according their NMR spectra. The complex 2 and its derivative 4 exist as unequal diastereomeric pairs according to the NMR. Fluxional NMR behavior is observed for 1, wherein the cod appears to partly dissociate and invert, for 2 and 3 where the cod exchange appears to involve a different mechanism being assisted by dissociation of one imine substituent, for 2 and 4 wherein allyl syn−syn, anti−anti exchange occurs between the diastereomers, and for 7 wherein the coordinated and uncoordinated imine groups exchange.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 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) | 0.003 | 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".