Molecular studies of the initiation and termination steps of the anionic polymerization of P=C bonds
| Autor: | Justin J. Kingsley, Tom H. H. Hsieh, Bastian Feldscher, Jennifer M. Wissenz, Bronwyn H. Gillon, Zhi Ming Kam, Derek P. Gates, Kevin J. T. Noonan, Joshua I. Bates |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Canadian Journal of Chemistry. 85:1045-1052 |
| ISSN: | 1480-3291 0008-4042 |
| DOI: | 10.1139/v07-121 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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