Impact of Steric Blocking on Diastereoselective C−H Activation of\nEthylbenzene by Cationic Platinum(II) Complexes with 7-Azaindolyl\nDerivative Ligands
Bibliographic record
Abstract
Ethylbenzene C−H activation reactions using the cationic compounds [Pt(BAB)(CH<sub>3</sub>)(L)]<sup>+</sup> and [Pt(BAM)(CH<sub>3</sub>)(L)]<sup>+</sup> generated in situ by the reaction of [(Et<sub>2</sub>O)<sub>2</sub>H][BAr‘<sub>4</sub>] with the parent molecules Pt(BAB)(CH<sub>3</sub>)<sub>2</sub> (<b>1</b>) and Pt(BAM)(CH<sub>3</sub>)<sub>2</sub> (<b>2</b>), respectively, have been examined (BAB = 1,2-bis(<i>N</i>-7-azaindolyl)benzene, BAM = bis(<i>N</i>-7-azaindolyl)methane). The impact of the steric blockage of the Pt\naxial coordination site by the BAB and BAM ligands on the regio- and diastereoselectivity of the\nethylbenzene C−H activation has been investigated. For both Pt complexes the benzylic C−H activation\nproducts were found to be thermodynamically favored, with the BAB complex showing a higher\nregioselectivity. In addition, both complexes display distinct diastereoselectivity in the formation of the\nη<sup>1</sup>-benzylic products [Pt(BAB)(CH<sub>3</sub>CN)(CH(Me)Ph)][BAr‘<sub>4</sub>] (<b>3</b>) and [Pt(BAM)(CH<sub>3</sub>CN)(CH(Me)Ph)][BAr‘<sub>4</sub>] (<b>4</b>), with the BAB complex showing a much higher diastereoselectivity. The structures of the\ndiastereomers have been established by single-crystal X-ray diffraction and 2D NOESY NMR analyses.\nThe two η<sup>3</sup> complexes [Pt(BAB)(η<sup>3</sup>-CH(Me)Ph)][BAr‘<sub>4</sub>] (<b>5</b>) and [Pt(BAM)(η<sup>3</sup>-CH(Me)Ph)][BAr‘<sub>4</sub>] (<b>6</b>)\nhave been characterized, and the structure of <b>5</b> has been determined by single-crystal X-ray diffraction\nanalysis. The η<sup>3</sup> complexes have been found to exist in two isomeric forms, with one isomer being\ndominant. NMR experiments established that the η<sup>3</sup> complexes <b>5</b> and <b>6</b> can be converted quantitatively\nto the corresponding η<sup>1</sup> complexes <b>3</b> and <b>4</b>, respectively, with the retention of the isomer (or diastereomer)\nratio. The results of this investigation are consistent with the η<sup>3</sup>-benzylic complex being the reaction\nintermediate in the formation of the η<sup>1</sup>-benzylic complex. The asymmetric blocking of the Pt axial\ncoordination site by the BAB and BAM ligands was found to be responsible for the observed\ndiastereoselectivity in ethylbenzene C−H activation.
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How this classification was reachedexpand
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 | 0.001 |
| 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) | 0.054 | 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 teacher head, 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".