Organic and organometallic derivatives of pentaphenylbenzene, C<sub>6</sub>Ph<sub>5</sub>X: correlation of peripheral phenyl ring orientations with the steric bulk of “X”
Bibliographic record
Abstract
A series of C6Ph5X compounds, including X = H, Br, CO2H, CO2R, C[Formula: see text]CPh, cis-BrC=C(Br)Ph, 2-bornenyl, and ferrocenyl, have been characterized by use of X-ray crystallography. Also, the first organometallic complexes of pentaphenylbenzene have been prepared by reaction with chromium hexacarbonyl to yield (η6-C6Ph5H)Cr(CO)3 complexes in which the metal tripod is attached either to an ortho peripheral ring or to the central ring. Crystalline pentaphenylbenzoic acid exists as a hydrogen-bonded dimer; however, the steric bulk of the substituents does not allow the carboxylic acid moieties to be linked directly but instead via two bridging methanol molecules. In the solid state, the orientation of the peripheral rings in bulky C6Ph5X systems is very sensitive to the size of the “X” substituents, such that the twist angle of the para ring responds inversely with increasing bulk of “X”, which drives the ortho rings farther out of the plane of the central ring. The relevance of these observations to correlated motion in molecular propellers, and ultimately to molecular machines, is discussed.
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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".