NHC Complexes of Osmium Clusters: A Structural and Reactivity Study
Bibliographic record
Abstract
A carbene transfer agent, 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene-silver(I)chloride ([IMes]AgCl), was treated with various osmium clusters. Reaction of ([IMes]AgCl) with [Os 3 (μ-H) 2 (CO) 10 ] gave [Os 3 (μ-H)(μ-Cl)(CO) 9 (IMes)] ( 1 ), an osmium N -heterocyclic carbene complex. The reaction of ([IMes]AgCl) with the cluster [Os 3 (CO) 10 (CH 3 CN) 2 ] yielded two products, [Os 3 (μ-Cl)(CO) 10 (μ-Ag(IMes)] ( 2 ) and [(IMes-H)][Os 3 (μ-Cl)(CO) 10 ](μ 4 -Ag)[Os 3 (μ-Cl)(CO) 10 ] ( 3 ). Compound ( 2 ) is a heterobimetallic carbene complex resulting from the complete incorporation of ([IMes]AgCl). Transmetalation using [(IMes)AgCl] and the cluster [Os 4 (μ-H) 4 (CO) 12 ] in the presence of trimethylamine- N -oxide resulted in the formation of [Os 4 (μ-H) 4 (CO) 11 ( n ·IMes)] ( 4 ), where ( n denotes normal carbene bonding, i.e., through C 2 ). [Os 4 (μ-H) 4 (CO) 10 (IMes) 2 ] ( 5 ) was formed using the activated cluster [Os 4 (μ-H) 4 (CO) 10 (CH 3 CN) 2 ] and [(IMes)AgCl]. Compound ( 5 ) was found to be sensitive to silica gel column chromatography in the presence of dichloromethane decomposing to [Os 4 (μ-H) 3 (μ-Cl)(CO) 11 (IMes)] ( 6 ), which possessed a butterfly metal skeleton. The ruthenium analogue of ( 4 ), [Ru 4 (μ-H) 4 (CO) 11 (IMes)] ( 7 ), was prepared and identified spectroscopically but was found to be thermally unstable. Thermolysis of ( 4 ) in benzene yielded four products. The abnormal carbene complex [Os 4 (μ-H) 4 (CO) 11 ( a ·IMes)] ( 10 ) ( a denotes abnormal carbene bonding through C 3 or C 4 ), an isomer of ( 4 ), and {Os 4 (μ-H)(CO) 10 [(η-C)N(Mes)C 2 H 2 NC 6 H 2 (CH 3 ) 2 (η 2 -C)(η-C)C 4 H 4 (η 2 -C)]} ( 11 ), an unusual complex resulting from the activation of benzene and activation of three C−H bonds on IMes, were isolated in modest yields. Two higher-nuclearity clusters, {Os 5 (μ 5 -C)(CO) 14 [η-C-η-NC 2 H 2 (Mes)]} ( 8 ) and [Os 6 (μ-H) 4 (μ 5 -C)(CO) 15 (IMes)] ( 9 ), both of which contain carbide ligands, were also isolated. {Os 4 (μ-H)(CO) 10 [(η-C)N(Mes)C 2 H 2 NC 6 H 2 (CH 3 ) 2 (η 2 -C)(η-C)CHC(CH 3 )C 2 H 2 (η 2 -C)]} ( 12 ), an analogue of ( 10 ), resulted from the thermolysis of ( 4 ) in toluene indicates that the reaction is potentially general and exhibits some regioselectivity. Crystal structure determinations were completed on all 11 osmium cluster complexes.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".