Carbon−Carbon Bond Formation by Cumulene Insertion into “Rh(μ-CH<sub>2</sub>)M” Moieties (M = Ru, Os): Roles of the Cumulenes and the Metals in Product Formation
Bibliographic record
Abstract
The reactions of allene, methylallene, and 1,1-dimethylallene with [RhM(CO) 4 (μ-CH 2 )(dppm) 2 ][X] (M = Os, X = BF 4 ( 1 ); M = Ru, X = CF 3 SO 3 ( 3 ); dppm = μ-Ph 2 PCH 2 PPh 2 ) in the presence of 1 equiv of trimethylamine oxide yield a variety of products. Under these conditions compounds 1 and 3 react with allene to yield the trimethylenemethane-bridged products [RhM(CO) 2 (μ-η 3:η 1 -C(CH 2 ) 3 )(dppm) 2 ][X] (M = Os ( 5 ), Ru ( 6 )), in which the trimethylenemethane fragment is η 1 -bound to the group 8 metal by one methylene group and η 3 -bound to Rh by the rest of the fragment. These compounds react with CO and PMe 3 to yield [RhM(CO) 2 L(μ-η 3:η 1 -C(CH 2 ) 3 )(dppm) 2 ][X] (L = CO, PMe 3 ), in which L is coordinated to Rh and the η 3:η 1 -binding mode of trimethylenemethane is retained. Although attack of L occurs at Rh for the Rh/Ru species, carbonyl attack in the Rh/Os compound initially occurs at Os with subsequent scrambling throughout the three carbonyl sites; attack of PMe 3 on the Rh/Os compound occurs at Rh. Methylallene reacts with 1 and Me 3 NO to give a species analogous to 5 and 6, having the methyl substituent on one of the terminal carbons of the allylic functionality. This methyl group is involved in an agostic interaction with Rh, which can be displaced by CO. The tricarbonyl complex [RhOs(CO) 3 (μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 2 ) reacts with 1,1-dimethylallene at −10°C to give [RhOs(CO) 3 (μ-η 1:η 1 -(CH 3 ) 2 CCCH 2 CH 2 )(dppm) 2 ][CF 3 SO 3 ], in which the dimethylvinyl group is adjacent to Rh, exo to the RhCCH 2 CH 2 Os dimetallacycle. At ambient temperature this species decomposes to give 1,1-dimethyl-1,3-butadiene. Compound 3 reacts with 1,1-dimethylallene in the presence of Me 3 NO to yield [RhRu(CO) 2 ((CH 3 ) 2 CCCH 2 CH 2 CO)(dppm) 2 ][CF 3 SO 3 ] ( 14 ), in which [2+1+1] coupling of the allene, the bridging methylene group, and a coordinated carbonyl has occurred. The dative bond from the bridging acyl moiety of 14 to Ru is displaced in reactions with H 2 and CO to give [RhRu(CO) 2 (C(O)CH 2 CH 2 C( C(CH 3 ) 2 ))(μ-H) 2 (dppm) 2 ][CF 3 SO 3 ] and [RhRu(CO) 3 (C(O)CH 2 CH 2 C( C(CH 3 ) 2 ))(dppm) 2 ][CF 3 SO 3 ], respectively. A rationalization of this chemistry is presented.
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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".