Carbon−Carbon Bond Formation Promoted by Adjacent Metal Centers: Regioselective Alkyne Insertions into a “Rh(μ-CH<sub>2</sub>)Ru” Moiety Yielding C<sub>3</sub>- and C<sub>5</sub>-Bridged Fragments
Bibliographic record
Abstract
The heterobinuclear complex [RhRu(CO) 3 (μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 2 ) (dppm = Ph 2 PCH 2 PPh 2 ), generated in situ from the tetracarbonyl precursor, reacts with the alkynes, dimethyl acetylenedicarboxylate, hexafluoro-2-butyne, and diethyl acetylenedicarboxylate to give the C 3 -bridged products [RhRu(CO) 3 (μ-η 1:η 1 -C(R) C(R)CH 2 )(dppm) 2 ][CF 3 SO 3 ] (R = CO 2 CH 3 ( 3 ), CF 3 ( 4 ), CO 2 CH 2 CH 3 ( 5 )), in which the alkynes have inserted into the Rh−C bond of the bridging methylene group. Compound 2 also reacts with 2-butyn-1-al diethylacetal and 2-butyn-1-ol, producing the insertion products [RhRu(CO) 3 (μ-η 1:η 1 -C(CH 3 ) C(R)CH 2 )(dppm) 2 ][CF 3 SO 3 ] (R = CH(OEt) 2 ( 6 ), CH 2 OH ( 7 )) analogous to compounds 3 − 5 . The regiochemistry of alkyne insertion in both cases has been established by 2-D NMR spectroscopy; the methyl substituent is adjacent to Rh, and the oxygen-containing substituent is adjacent to the methylene group. Attempts to generate an isomer of 3 by the reverse sequence of methylene insertion into the Rh−C bond of the alkyne-bridged species [RhRu(CO) 3 (μ-η 1:η 1 -C(CO 2 CH 3 ) C(CO 2 CH 3 ))(dppm) 2 ][X] (X = BF 4 ( 8a ), CF 3 SO 3 ( 8b )) failed with no reaction occurring, although reaction of the dicarbonyl analogue, [RhRu(OSO 2 CF 3 )(CO) 2 (μ-η 1:η 1 -C(CO 2 CH 3 ) C(CO 2 CH 3 ))(dppm) 2 ], with CH 2 N 2 results in methylene insertion into the Rh−Ru bond to give [RhRu(OSO 2 CF 3 )(CO) 2 (μ-CH 2 )(μ-η 1:η 1 -C(CO 2 CH 3 ) C(CO 2 CH 3 ))(dppm) 2 ] ( 10 ). Reaction of 3 with trimethylamine- N -oxide results in loss of a carbonyl and a rearrangement of the C 3 -bridged group, affording [RhRu(CO) 2 (μ-η 1:η 3 -CHC(CO 2 CH 3 ) CH(CO 2 CH 3 ))(dppm) 2 ][CF 3 SO 3 ] ( 11 ). Propargyl alcohol reacts with 2, affording a double-insertion product [RhRu(CO) 2 (μ-η 2:η 4 -CH C(CH 2 OH)CH C(CH 2 OH)CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 12 ) with incorporation of two propargyl alcohol units in a head-to-tail arrangement. The structures of compounds 4, 8a, and 12 were determined by X-ray methods.
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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) | 0.002 | 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".