Crystal chemistry of tetraradial species. Part 10. Tilting at windmills: conformations of the tetraphenyl species ZPh<sub>4</sub><sup>0, ±1</sup> (Z = B, C, N)
Bibliographic record
Abstract
The equilibrium geometries of the isoelectronic ZPh40, ±1 (Z = B, C, N) molecules have been optimized, in S4 and D2d symmetries, at the HF/6-31G(d,p) and B3LYP/6-31G(d,p) levels, with the phenyl rings constrained to be planar. The ground-state conformations of all three species are shown to be of S4 symmetry, but the difference of the energies of the S4 and the D2d conformations is estimated to amount to only ~1 kcal mol1, with a barrier to concerted rotational reorientation of the phenyl rings of ~5.0 kcal mol1 for BPh4, ~6.4 kcal mol1 for CPh4, and ~7.9 kcal mol1 for NPh+4. A redetermination of the crystal structure of CPh4 from 60°C X-ray data agrees with the results of previous determinations at ambient temperature; the CPh4 molecule in the crystal is slightly compressed along the S4 axis relative to the free molecule, otherwise the geometries of the two are essentially the same. Correlations between the optimized geometric parameters of the ZPh40, ±1 molecules have been examined and analyzed in detail, as have the substitution-induced changes in the geometry of the phenyl ring. The results confirm and strengthen the conclusions from the statistical studies by Domenicano et al. on the geometry of benzene rings monosubstituted by atoms of elements from the first row of the Periodic system.Key words: tetraphenylborate, tetraphenylmethane, tetraphenylammonium, ab initio molecular geometries.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 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".