Chemical and Electrochemical Oxidation of <i>Tris</i>(3,5‐di‐<i>tert</i>‐butylphenyl)phosphine – High <i>Z′</i> Crystal Structures and Conformational Effects Associated with Bulky <i>meta</i> Substituents
Bibliographic record
Abstract
Synthesis and single‐crystal X‐ray diffraction structures of (3,5‐ t Bu 2 ‐C 6 H 3 ) 3 P, (3,5‐ t Bu 2 ‐C 6 H 3 ) 3 PO · H 2 O, (3,5‐ t Bu 2 ‐C 6 H 3 ) 3 PS and (3,5‐ t Bu 2 ‐C 6 H 3 ) 3 PSe are reported. The structure of (3,5‐ t Bu 2 ‐C 6 H 3 ) 3 P has Z′ = 4, with both M and P enantiomers of a helical conformation and a conformation with one flat ring in the same lattice. The pyramidality index, Σ{∠CPC}, is smaller for the helical compared to the flat conformers. All four have structures that are more pyramidal than the corresponding Ph 3 P(E) derivatives, which is attributed to stronger intramolecular dispersion forces. The oxide crystallizes with Z′ = 2 as a water‐bridged dimer that is the most separated such dimer amongst 26 known structures, providing evidence for a distal (or perimeter) steric effect. Cyclic voltammetry in CH 3 CN/[ n Bu 4 N][ClO 4 ] indicated anodic peak potentials of +0.785 V for (3,5‐ t Bu 2 ‐C 6 H 3 ) 3 P, +0.745 for (3,5‐Me 2 ‐C 6 H 3 ) 3 P, +0.735 V for (4‐MeO‐3,5‐Me 2 ‐C 6 H 2 ) 3 P and +0.535 V for (4‐MeO‐C 6 H 4 ) 3 P, all relative to Fc +/0 . On this scale, Ph 3 P oxidizes at +1.04 V. The unexpectedly high oxidation potentials for the first three phosphines is attributed to a more pyramidal structure resulting in lowering of the HOMO energy compared to expectations from Hammett constants and 1 J (P,Se) NMR coupling constants.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 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".