Molecular studies of the initiation and termination steps of the anionic polymerization of P=C bonds
Bibliographic record
Abstract
The initiation and termination steps of the anionic polymerization of P=C bonds have been modeled. The initiation step was investigated through the stoichiometric reaction of MesP=CPh2 (1) with RLi (R = Me or n-Bu). In each case, the addition was highly regioselective with the formal attack of R– at phosphorus to give the carbanion Li[Mes(R)P–CPh2] (3a, R = Me; 3b, R = n-Bu). To simulate the termination step in the anionic polymerization of 1, carbanions 3a and 3b were quenched in situ with various electrophiles. Through these reactions, several new tertiary phosphines have been prepared, namely, Mes(Me)P–CPh2H (4a), Mes(n-Bu)P–CPh2H (4b), Mes(Me)P–CPh2Me (6a), Mes(Me)P–CPh2–P(NEt2)2 (7a), Mes(Me)P–CPh2–SiMe2H (8a), and Mes(Me)P–CPh2–SiMe3 (9a). In addition, compounds 4a, 7a, 8a, and 9a were characterized by X-ray crystallography. Most of the metrical parameters are typical of tertiary phosphines; however, the P–CPh2H bonds were elongated in all cases reflecting the considerable steric bulk surrounding this bond. Unexpectedly, an unusually large 31P–31P coupling constant (2JPP > 200 Hz) was observed for 7a both in solution and the solid state. This observation may be rationalized by a through space P···P interaction. This rationale is further supported by the short P···P distance [P(1)—P(2) = 2.966(1) Å; cf. Σ rvdw = 3.7 Å] and a small P–C–P bond angle for 7a [P(1)–C(11)–P(1) = 99.17(9)°].Key words: phosphaalkenes, phosphorus polymers, phosphines, anionic polymerization.
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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 | 0.001 |
| 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".