1,2-<i>Bis</i>(2,6-diisopropylphenyl)diphosphane: a structural, spectroscopic, and computational investigation
Bibliographic record
Abstract
The title compound Dipp(H)P–P(H)Dipp where Dipp = 2,6-diisopropylyphenyl has been prepared starting from DippPH2 via DippPHLi reacting 2:1 with BrCH2CH2Br. A high-resolution single-crystal X-ray diffraction study at 153 ± 2 K provides an accurate description of the structure in the solid state, only the fourth dihydro diorganophosphane to have been so characterized. The Raman spectrum of the solid shows an intense, broad peak for P–H stretching at 2314 cm−1 and two peaks at 460 and 450 cm−1 for P–P stretching, assignments confirmed by RHF/6-31G+(3d,2p) frequency calculations undertaken on the anti conformers. 31P, 31P{1H }, 1H{31P}, and 13C{1H } solution NMR spectra in CDCl3 are consistent with the presence of 58% meso and 42% rac diastereomers. Analysis of their AA′XX′ spin systems enabled calculation of 1JPP′ values of (–)189 and (–)205 Hz, respectively. A B3LYP/6-31G(d,p) computational analysis of the energetics of rotation about the P–P bond in both diastereomers shows that the anti and two gauche conformers are likely to be populated approximately equally in each. The resulting average ϕ angles (torsions of the phosphorus lone pairs) are 110° for meso and 103° for rac; the smaller ϕ angle fits with the larger 1JPP′ value for the rac isomer.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".