Alkyne/Methylene Coupling Reactions at Adjacent Rh/Os Centers: Stepwise Transformations from C<sub>1</sub>- through C<sub>4</sub>-Bridged Species
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Bibliographic record
Abstract
Reaction of the methylene-bridged complex [RhOs(CO) 3 (μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] (dppm = μ-Ph 2 PCH 2 PPh 2 ) with dimethyl acetylenedicarboxylate or hexafluorobutyne results in alkyne insertion into the Rh−CH 2 bond, yielding [RhOs(CO) 3 (μ-η 1:η 1 -RC C(R)CH 2 )(dppm) 2 ][CF 3 SO 3 ] (R = CO 2 Me ( 5 ), CF 3 ( 6 )). Carbonyl removal from each of these species results in a Rh-bound carbonyl being replaced by a triflate ion. Reaction of 5 with diazomethane results in CH 2 insertion into the Rh−C(R) bond with accompanying C−H activation of the original osmium-bound CH 2 group, yielding [RhOs(CO) 3 (μ-η 1:η 1 -CH 2 C(R) C(R)CH)(μ-H)(dppm) 2 ][CF 3 SO 3 ] (R = CO 2 Me). Reaction of the alkyne-bridged species [RhOs(CO) 3 (μ-η 1:η 1 -RC CR)(dppm) 2 ][CF 3 SO 3 ] (R = CO 2 Me) with diazomethane at −78 °C yields [RhOs(CO) 3 (μ-η 1:η 1 -CH 2 C(R) CR)(dppm) 2 ][CF 3 SO 3 ] ( 12 ), which upon warming to ambient temperature, in the absence of diazomethane, undergoes alkyne deinsertion to yield [RhOs(CO) 3 (η 2 -RC⋮CR)(μ-CH 2 )(dppm) 2 ][CF 3 SO 3 ] ( 13 ). This species and the inserted product ( 12 ) appear to be in equilibrium, so reaction of 13 with diazomethane proceeds via 12 to give [RhOs(CO) 3 (η 1:η 1 -CH 2 CH 2 C(R) CR)(dppm) 2 ][CF 3 SO 2 ] ( 14 ), in which the hydrocarbyl fragment is chelating to Os and interacting with Rh via an agostic interaction with one of the Os-bound CH 2 hydrogens. Upon standing for weeks, or more rapidly upon refluxing, compound 14 transforms into an isomer ( 15 ) in which the C 4 unit has migrated from sites on Os adjacent to Rh to sites on Os remote from Rh. An X-ray structure determination of compound 15 as the BF 4 - salt confirms the geometry of this final species. Reaction of the hexafluorobutyne-bridged species [RhOs(CO) 3 (μ-η 1:η 1 -RC CR)(dppm) 2 ][CF 3 SO 3 ] (R = CF 3 ) with diazomethane does not give a product analogous to that described for dimethyl acetylenedicarboxylate, but yields the isomer 6 . These carbon−carbon bond forming processes are discussed.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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 it