Impact of Steric Blocking on Diastereoselective C−H Activation of Ethylbenzene by Cationic Platinum(II) Complexes with 7-Azaindolyl Derivative Ligands
Bibliographic record
Abstract
Ethylbenzene C−H activation reactions using the cationic compounds [Pt(BAB)(CH 3 )(L)] + and [Pt(BAM)(CH 3 )(L)] + generated in situ by the reaction of [(Et 2 O) 2 H][BAr‘ 4 ] with the parent molecules Pt(BAB)(CH 3 ) 2 ( 1 ) and Pt(BAM)(CH 3 ) 2 ( 2 ), respectively, have been examined (BAB = 1,2-bis( N -7-azaindolyl)benzene, BAM = bis( N -7-azaindolyl)methane). The impact of the steric blockage of the Pt axial coordination site by the BAB and BAM ligands on the regio- and diastereoselectivity of the ethylbenzene C−H activation has been investigated. For both Pt complexes the benzylic C−H activation products were found to be thermodynamically favored, with the BAB complex showing a higher regioselectivity. In addition, both complexes display distinct diastereoselectivity in the formation of the η 1 -benzylic products [Pt(BAB)(CH 3 CN)(CH(Me)Ph)][BAr‘ 4 ] ( 3 ) and [Pt(BAM)(CH 3 CN)(CH(Me)Ph)][BAr‘ 4 ] ( 4 ), with the BAB complex showing a much higher diastereoselectivity. The structures of the diastereomers have been established by single-crystal X-ray diffraction and 2D NOESY NMR analyses. The two η 3 complexes [Pt(BAB)(η 3 -CH(Me)Ph)][BAr‘ 4 ] ( 5 ) and [Pt(BAM)(η 3 -CH(Me)Ph)][BAr‘ 4 ] ( 6 ) have been characterized, and the structure of 5 has been determined by single-crystal X-ray diffraction analysis. The η 3 complexes have been found to exist in two isomeric forms, with one isomer being dominant. NMR experiments established that the η 3 complexes 5 and 6 can be converted quantitatively to the corresponding η 1 complexes 3 and 4, respectively, with the retention of the isomer (or diastereomer) ratio. The results of this investigation are consistent with the η 3 -benzylic complex being the reaction intermediate in the formation of the η 1 -benzylic complex. The asymmetric blocking of the Pt axial coordination site by the BAB and BAM ligands was found to be responsible for the observed diastereoselectivity in ethylbenzene C−H activation.
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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 | 0.001 |
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".