Two tris(3,5-disubstituted phenyl)phosphines and their isostructural P<sup>V</sup> oxides
Bibliographic record
Abstract
The crystal structures of tris(3,5-dimethylphenyl)phosphine (C24H27P), (I), tris(3,5-dimethylphenyl)phosphine oxide (C24H27OP), (II), tris(4-methoxy-3,5-dimethylphenyl)phosphine (C27H33O3P), (III), and tris(4-methoxy-3,5-dimethylphenyl)phosphine oxide (C27H33O4P), (IV), are reported. The strucure of (III) has been described before [Romain et al. (2000). Organometallics, 19, 2047–2050], but it is rereported here on the basis of modern area-detector data and to facilitate comparison with the other structures reported here. Compounds (I) and (II) crystallize isostructurally in P21/c. Similarly, (III) and (IV) crystallize isostructurally in Pbca. The conformations of (I) and (II) in the solid state deviate strongly from helical, whereas those of (III) and (IV) are found to be closer to an ideal threefold rotational symmetry. The pyramidality indices, ∑(C—P—C), are 305.35 (16), 317.23 (15), 307.2 (4) and 318.67 (18)° for (I), (II), (III) and (IV), respectively. Each is found to be more pyramidal than Ph3P or Ph3PO. Hybrid DFT calculations incorporating terms for dispersion provide evidence that the causes of the increased pyramidality, despite the 3,5-dimethyl group substitution, include dispersion interactions. The calculated ∑(C—P—C) values are 304.8° for both (I) and (III) and 317.4° for both (II) and (IV), with no difference arising from the substitution at ring position 4.
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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) | 0.001 | 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".