Reactivity of Fe and Ru Complexes of Picolyl-Substituted <i>N</i>-Heterocyclic Carbene Ligand: Diverse Coordination Modes and Small Molecule Binding
Bibliographic record
Abstract
Complexes [MClCp*(HL)] ( 1[Fe] / 1[Ru] ) (where HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-2-ylidene) were synthesized from the reaction of in situ generated HL ligand and [FeClCp*(TMEDA)] (where TMEDA is N, N, N ′, N ′-tetramethylethylenediamine) or [RuClCp*] 4, respectively. The deprotonation of 1[Fe] / 1[Ru] with 1 equiv of LiHMDS led to cyclometalation through the o -Me of the mesityl group, forming [MCp*(L-κ C,κ C ′,κ N )] 2[Fe] / 2[Ru] . The coordinatively unsaturated compounds [MCp*(HL)]BPh 4 3[Fe] / 3[Ru] were prepared from 1[Fe] / 1[Ru] and halide scavenger NaBPh 4 . Complex 3[Ru] showed agostic interactions between the o -Me group of the mesityl moiety and the metal center in solution and the solid state. When the vacant coordination site of 3[Fe] / 3[Ru] is occupied by CO, the resulting [MCp*(CO)(HL)]BPh 4 4[Fe] / 4[Ru] can be deprotonated with 1 equiv of KHMDS at the pyridylic position to afford complexes [MCp*L′(CO)] 5[Fe] / 5[Ru], where the L′ – ligand chelates to the metal center through the nitrogen donor atom of the dearomatized pyridine ring and the carbene carbon. Complex 2[Fe] reacted rapidly with CO to afford the simple ligand substitution product [FeCp*(L-κ C,κ C ′)(CO)] 6[Fe], where the L – acts as a bidentate chelating ligand through the carbene carbon and benzylic carbon. Under the same condition, the reaction of 2[Ru] with CO forms [RuCp*L″(CO)] 7[Ru], where the L″ – ligand (an isomer of L – and L′ – ) chelates to the metal center through the carbene carbon and a pyridyl carbon. Complexes 3[Fe] / 3[Ru] reversibly bind dinitrogen to form [MCp*(HL)(N 2 )]BPh 4 8[Fe] / 8[Ru] . 3[Ru] reversibly binds dihydrogen to give [MCp*(H 2 )(HL)]BPh 4 9[Ru], while no reaction was observed between 3[Fe] and H 2 . The reaction of 3[Ru] with dioxygen led to the isolation of a stable side-on O 2 complex [RuCp*(HL)(O 2 )]BPh 4 10[Ru], while the reaction of 3[Fe] with dioxygen led to an intractable mixture of products.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".