Strain-Induced Ring-Opening Polymerization of Ferrocenylorganocyclotriphosphazenes: A New Synthetic Route to Poly(organophosphazenes)

Harry R. Allcock, Jeffrey A. Dodge, Ian Manners, Geoffrey H. Riding

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The strained transannular ferrocenylcyclotriphosphazenes N3P3(OCH2CF3)4(η-CsH4)2Fe, N3P3R(0CH2CF3)3(η-C5H4)2Fe [R = OPh, R = Me, R = Ph (R geminal to Cp), and R = Ph (nongeminal to Cp)], and N3P3R2(OCH2CF3)2(η-C5H4)2Fe [R = Ph (geminal to Cp) and R = Ph (nongeminal to Cp)] undergo ring-opening polymerization when heated at 250 °C in the presence of a small amount (1%) of (NPC12)3, which functions as a polymerization initiator. The cyclic trimers N3P3-(OPh)(OCH2CF3)3(η-C5H4)2Fe, N3P3Me(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph2(OCH2CF3)2(η-C5H4)2Fe (Ph groups nongeminal to Cp) also polymerize at 250 °C but in the absence of (NPC12)3. These transformations are the first examples of uncatalyzed ring-opening polymerization of cyclic phosphazenes that lack phosphorus-halogen bonds. By contrast, the sterically crowded cyclotriphosphazene N3P3(OPh)4(η-C5H4)2Fe undergoes ring expansion to the corresponding cyclic hexamer when heated at 250 °C in the presence or absence of (NPC12)3, but it does not polymerize. When heated in the absence of (NPC12)3, N3P3(OCH2CF3)4(η-C5H4)2Fe, N3P3(OPh)(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph(OCH2CF3)3(η-C5H4)2Fe (Ph nongeminal to Cp) also undergo ring expansion to form the corresponding cyclic hexamers. The Lewis acid BC13 initiates the ring-opening polymerization of N3P3(OCH2CF3)4(η-C5H4)2Fe and catalyzes the ring expansion of N3P3(OPh)4(η-C5H4)2Fe. Possible explanations for the differences in thermal behavior are given. The implications of these results for the mechanisms of phosphazene ring-opening polymerization and ring-ring equilibration are also discussed.

Original languageEnglish (US)
Pages (from-to)9596-9603
Number of pages8
JournalJournal of the American Chemical Society
Volume113
Issue number25
DOIs
StatePublished - Dec 1 1991

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Ring opening polymerization
Polymerization
Lewis Acids
Halogens
Phosphorus
Acids
Hot Temperature

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

@article{7e022a53890445c4b36f96f2adbd111e,
title = "Strain-Induced Ring-Opening Polymerization of Ferrocenylorganocyclotriphosphazenes: A New Synthetic Route to Poly(organophosphazenes)",
abstract = "The strained transannular ferrocenylcyclotriphosphazenes N3P3(OCH2CF3)4(η-CsH4)2Fe, N3P3R(0CH2CF3)3(η-C5H4)2Fe [R = OPh, R = Me, R = Ph (R geminal to Cp), and R = Ph (nongeminal to Cp)], and N3P3R2(OCH2CF3)2(η-C5H4)2Fe [R = Ph (geminal to Cp) and R = Ph (nongeminal to Cp)] undergo ring-opening polymerization when heated at 250 °C in the presence of a small amount (1{\%}) of (NPC12)3, which functions as a polymerization initiator. The cyclic trimers N3P3-(OPh)(OCH2CF3)3(η-C5H4)2Fe, N3P3Me(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph2(OCH2CF3)2(η-C5H4)2Fe (Ph groups nongeminal to Cp) also polymerize at 250 °C but in the absence of (NPC12)3. These transformations are the first examples of uncatalyzed ring-opening polymerization of cyclic phosphazenes that lack phosphorus-halogen bonds. By contrast, the sterically crowded cyclotriphosphazene N3P3(OPh)4(η-C5H4)2Fe undergoes ring expansion to the corresponding cyclic hexamer when heated at 250 °C in the presence or absence of (NPC12)3, but it does not polymerize. When heated in the absence of (NPC12)3, N3P3(OCH2CF3)4(η-C5H4)2Fe, N3P3(OPh)(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph(OCH2CF3)3(η-C5H4)2Fe (Ph nongeminal to Cp) also undergo ring expansion to form the corresponding cyclic hexamers. The Lewis acid BC13 initiates the ring-opening polymerization of N3P3(OCH2CF3)4(η-C5H4)2Fe and catalyzes the ring expansion of N3P3(OPh)4(η-C5H4)2Fe. Possible explanations for the differences in thermal behavior are given. The implications of these results for the mechanisms of phosphazene ring-opening polymerization and ring-ring equilibration are also discussed.",
author = "Allcock, {Harry R.} and Dodge, {Jeffrey A.} and Ian Manners and Riding, {Geoffrey H.}",
year = "1991",
month = "12",
day = "1",
doi = "10.1021/ja00025a026",
language = "English (US)",
volume = "113",
pages = "9596--9603",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "25",

}

Strain-Induced Ring-Opening Polymerization of Ferrocenylorganocyclotriphosphazenes : A New Synthetic Route to Poly(organophosphazenes). / Allcock, Harry R.; Dodge, Jeffrey A.; Manners, Ian; Riding, Geoffrey H.

In: Journal of the American Chemical Society, Vol. 113, No. 25, 01.12.1991, p. 9596-9603.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Strain-Induced Ring-Opening Polymerization of Ferrocenylorganocyclotriphosphazenes

T2 - A New Synthetic Route to Poly(organophosphazenes)

AU - Allcock, Harry R.

AU - Dodge, Jeffrey A.

AU - Manners, Ian

AU - Riding, Geoffrey H.

PY - 1991/12/1

Y1 - 1991/12/1

N2 - The strained transannular ferrocenylcyclotriphosphazenes N3P3(OCH2CF3)4(η-CsH4)2Fe, N3P3R(0CH2CF3)3(η-C5H4)2Fe [R = OPh, R = Me, R = Ph (R geminal to Cp), and R = Ph (nongeminal to Cp)], and N3P3R2(OCH2CF3)2(η-C5H4)2Fe [R = Ph (geminal to Cp) and R = Ph (nongeminal to Cp)] undergo ring-opening polymerization when heated at 250 °C in the presence of a small amount (1%) of (NPC12)3, which functions as a polymerization initiator. The cyclic trimers N3P3-(OPh)(OCH2CF3)3(η-C5H4)2Fe, N3P3Me(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph2(OCH2CF3)2(η-C5H4)2Fe (Ph groups nongeminal to Cp) also polymerize at 250 °C but in the absence of (NPC12)3. These transformations are the first examples of uncatalyzed ring-opening polymerization of cyclic phosphazenes that lack phosphorus-halogen bonds. By contrast, the sterically crowded cyclotriphosphazene N3P3(OPh)4(η-C5H4)2Fe undergoes ring expansion to the corresponding cyclic hexamer when heated at 250 °C in the presence or absence of (NPC12)3, but it does not polymerize. When heated in the absence of (NPC12)3, N3P3(OCH2CF3)4(η-C5H4)2Fe, N3P3(OPh)(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph(OCH2CF3)3(η-C5H4)2Fe (Ph nongeminal to Cp) also undergo ring expansion to form the corresponding cyclic hexamers. The Lewis acid BC13 initiates the ring-opening polymerization of N3P3(OCH2CF3)4(η-C5H4)2Fe and catalyzes the ring expansion of N3P3(OPh)4(η-C5H4)2Fe. Possible explanations for the differences in thermal behavior are given. The implications of these results for the mechanisms of phosphazene ring-opening polymerization and ring-ring equilibration are also discussed.

AB - The strained transannular ferrocenylcyclotriphosphazenes N3P3(OCH2CF3)4(η-CsH4)2Fe, N3P3R(0CH2CF3)3(η-C5H4)2Fe [R = OPh, R = Me, R = Ph (R geminal to Cp), and R = Ph (nongeminal to Cp)], and N3P3R2(OCH2CF3)2(η-C5H4)2Fe [R = Ph (geminal to Cp) and R = Ph (nongeminal to Cp)] undergo ring-opening polymerization when heated at 250 °C in the presence of a small amount (1%) of (NPC12)3, which functions as a polymerization initiator. The cyclic trimers N3P3-(OPh)(OCH2CF3)3(η-C5H4)2Fe, N3P3Me(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph2(OCH2CF3)2(η-C5H4)2Fe (Ph groups nongeminal to Cp) also polymerize at 250 °C but in the absence of (NPC12)3. These transformations are the first examples of uncatalyzed ring-opening polymerization of cyclic phosphazenes that lack phosphorus-halogen bonds. By contrast, the sterically crowded cyclotriphosphazene N3P3(OPh)4(η-C5H4)2Fe undergoes ring expansion to the corresponding cyclic hexamer when heated at 250 °C in the presence or absence of (NPC12)3, but it does not polymerize. When heated in the absence of (NPC12)3, N3P3(OCH2CF3)4(η-C5H4)2Fe, N3P3(OPh)(OCH2CF3)3(η-C5H4)2Fe, and N3P3Ph(OCH2CF3)3(η-C5H4)2Fe (Ph nongeminal to Cp) also undergo ring expansion to form the corresponding cyclic hexamers. The Lewis acid BC13 initiates the ring-opening polymerization of N3P3(OCH2CF3)4(η-C5H4)2Fe and catalyzes the ring expansion of N3P3(OPh)4(η-C5H4)2Fe. Possible explanations for the differences in thermal behavior are given. The implications of these results for the mechanisms of phosphazene ring-opening polymerization and ring-ring equilibration are also discussed.

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