Alkyne/Methylene Coupling at Adjacent Iridium/Osmium Centers: Facile Carbon−Carbon and Carbon−Oxygen Bond Formation
Bibliographic record
Abstract
The methylene-bridged complex [IrOs(CO) 4 (μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] (dppm = μ-Ph 2 PCH 2 PPh 2 ) ( 3 ) can be synthesized by the addition of diazomethane to [IrOs(CO) 5 (dppm) 2 ][CF 3 SO 3 ] ( 1 ) or [IrOs(CO) 4 (dppm) 2 ][CF 3 SO 3 ] ( 2 ). Reaction of 3 with dimethyl acetylenedicarboxylate (DMAD) leads to the insertion of the alkyne into the iridium−carbon bond, yielding both [IrOs(CO) 4 (μ-κ 1:κ 1 -C(CO 2 CH 3 )═C(CO 2 CH 3 )CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 5 ) and [IrOs(CO) 3 (μ-κ 1:κ 1 -C(CO 2 CH 3 )═C(CO 2 CH 3 )CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 6 ), each of which can be obtained as the exclusive product under either CO or an Ar purge, respectively. Hexafluorobutyne (HFB) fails to react with 3, but reacts with [IrOs(CO) 3 (μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 4 ) yielding [IrOs(CO) 3 (μ-κ 1:κ 1 -C(CF 3 )═C(CF 3 )CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 7 ). Reaction of 7 with diazomethane results in the insertion of a second methylene unit into the iridium−carbon bond, yielding [IrOs(CO) 3 (μ-κ 1:κ 1 -CH 2 (CF 3 )C═C(CF 3 )CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 9 ), which can be characterized by NMR spectroscopy only at low temperatures owing to deinsertion of the iridium-bound methylene group at ambient temperature. Compound 6 also reacts with diazomethane but in this case results in the formation of a new carbon−oxygen bond between the newly introduced methylene unit and a carbonyl oxygen of the inserted DMAD fragment. This bond formation is accompanied by carbon−hydrogen bond activation of the original osmium-bound methylene group, yielding [IrOs(CO) 3 (μ-H)(μ-κ 1:κ 1:κ 1 -CH 2 OC(OCH 3 )═CC(CO 2 CH 3 )═CH)(dppm) 2 ][CF 3 SO 3 ] ( 8 ). Attempts to insert a methylene unit into the iridium−carbon bond of the alkyne-bridged complexes [IrOs(CO) 3 (μ-κ 1:κ 1 -RC═CR)(dppm) 2 ][CF 3 SO 3 ] (R = CO 2 Me ( 12 ), CF 3 ( 13 )) yields the C 3 -bridged complex [IrOs(CO) 3 (μ-κ 1:κ 1 -CH 2 (CF 3 )C═CCF 3 )(dppm) 2 ][CF 3 SO 3 ] ( 14 ) in the case of 13, but no further methylene incorporation is observed. Compound 12 reacts with diazomethane to give a number of unidentified products under a variety of conditions. The reactivities of the aforementioned complexes are compared to that of related late metal combinations.
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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) | 0.001 | 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 | 0.001 |
| Research integrity | 0.001 | 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".