Dimeric Rhodium–Ethylene NHC Complexes As Reactive Intermediates for the Preparation of Tetra-heteroleptic NHC Complexes
Bibliographic record
Abstract
Dimeric rhodium complexes with various N-heterocyclic carbene (NHC) ligands have been synthesized and fully characterized. X-ray analysis unambiguously confirms the bimetallic nature of these complexes, and in all cases one molecule of ethylene is coordinated to each metal center in an η 2 -fashion. The Rh atoms are also coordinated to one NHC ligand and are interconnected by two μ-chlorine bridges. The dimeric nature of the complexes is most likely stabilized due to the significant steric bulk around the metal centers provided by the carbene ligands. Consistent with this, modulating the steric properties and backbone saturation of the ligands was shown to have a significant effect on the stability and geometry of the complexes. Treatment of the carbene dimers with ligands such as PPh 3 results in cleavage of the dimers and a unique synthesis of tetra-heteroleptic complexes of the general formula [ClRh(NHC)(PR 3 )(CH 2 ═CH 2 )]. The stabilities of these compounds have been assessed, and although decomposition to Wilkinson’s complex is observed upon treatment with an excess of phosphine for prolonged times, the presence of the ethylene ligand provides greatly increased stability compared with the bis-phosphine analogues [ClRh(NHC)(PPh 3 ) 2 ].
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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; 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".