Diphosphiranium (P<sub>2</sub>C) or Diphosphetanium (P<sub>2</sub>C<sub>2</sub>) Cyclic Cations: Different Fates for the Electrophile-Initiated Cyclodimerization of a Phosphaalkene
Bibliographic record
Abstract
The synthesis and crystallographic characterization of two new classes of cationic three- and four-membered organophosphorus heterocycles are reported. Treating phosphaalkene tBuP=CHtBu (1) with triflic acid (2:1) afforded an unprecedented asymmetric diphosphiranium triflate [tBuP-CH(tBu)-P(tBu)(CH2tBu)]OTf (2). Surprisingly, the analogous reaction of tBuP=CHtBu with methyl triflate (2:1) afforded a 1,3-diphosphetanium salt [tBu(Me)P-CH(tBu)-P(tBu)-CH(tBu)]OTf (3a). Structural characterization of these novel P2C and P2C2 rings confirmed their identity, and the metrical parameters were consistent with the strain expected for these ring systems. In preliminary mechanistic investigations by NMR spectroscopy, phosphenium species [tBuPCH2tBu]OTf (4) was detected in the stoichiometric reaction of 1 with HOTf while methylenephosphonium [Me(tBu)P=CHtBu]OTf (5) was observed when 1 was treated with MeOTf. The opposite reactivity observed when the P=C bond is treated with MeOTf compared that with HOTf is surprising and, to our knowledge, has not been observed previously in phosphaalkene chemistry. In addition to their fundamental interest, we are interested in these species as ring-closed forms of the propagating species in the cationic polymerization of P=C bonds.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".