<scp>Group‐IV‐based</scp> selective <scp>CH</scp> bond activation of a diamondoid—A density functional theory study
Bibliographic record
Abstract
Abstract Selective synthetic modifications on diamondoids (well‐defined molecular nano‐diamonds) are difficult. Group IV organometallic complexes are promising systems for CH bond activation. We study the CH bond activation of the hard‐to‐activate CH2 positions of the adamantyl group (the smallest diamondoid) using density functional theory. As a platform for activation, we tether the adamantyl group to the cyclopentadienyl in a substituted bis‐cyclopentadienyl group IV metal diphenyl complex. The mechanism proposed in the experimental paper reporting the activation of C(Me)2‐Ph or t‐Bu groups using Zr(IV) involves an η2‐benzyne complex intermediate. Our computational work confirms the two‐step mechanism proposed for activation of C(Me)2‐Ph or t‐Bu using Zr(IV) and further extends it to Ti(IV) and Hf(IV). The first step forms the benzyne complex. In the second step, the cyclopentadienyl‐bound group is activated through a mechanism that closely resembles a σ‐bond metathesis when the benzyne complex is described as a metallacyclopropene We demonstrate through computations that the two‐step reaction can be successfully applied to the adamantyl group. CH bond activation of adamantyl is found to be thermodynamically and kinetically feasible. The important question of regioselectivity is addressed. We predict that α‐CH bond activation will be achievable with Ti (thermodynamic control), and selective γ‐CH bond activation with Zr (kinetic or thermodynamic control).
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".