New Insights into Poly(Dichlorophosphazene) Synthesis via Me3Si─N═PCl3 Polymerization: An Experimental and Theoretical Study
4 affiliations
- 1Institute of Chemistry University of Rostock Rostock Germany
- 2Institute of Polymer Chemistry Johannes Kepler University Linz Austria
- 3Institute For Biomedical Engineering University Medical Center Rostock Rostock Germany
- 4Leibniz‐Institute For Catalysis e.V. Rostock Germany
Abstract
Polyphosphazenes are a unique class of polymers, notable for their versatile functionalization and distinctive properties arising from their alternating phosphorus–nitrogen backbone. However, the synthesis of their primary precursor, poly(dichlorophosphazene) ([NPCl2] n ), is notoriously delicate and poorly understood, limiting broader adoption. Herein, we reinvestigate the controlled polymerization of Me3Si─N═PCl3 using quantum mechanical calculations to elucidate its underlying mechanism. Guided by these insights, we optimized the experimental conditions and achieved significantly higher molecular weights than previously reported for this polymerization route. Polymerization occurs at ambient temperature only upon addition of a cationic initiator, such as Ph3PCl2, yielding [NPCl2] n chains of varying lengths. Experiments and DFT calculations indicate that initiation proceeds via three key steps: (i) dissociation of Ph3PCl2 into [Ph3PCl]+ and Cl− ions, dependent on the reaction medium; (ii) nucleophilic attack of Cl− on Me3Si─N═PCl3, producing [N═PCl3]− and eliminating Me3SiCl; (iii) reaction of [N═PCl3]− with [Ph3PCl]+ to form Ph3P─NPCl4, which dissociates to generate additional reactive species, propagating chain growth. The elimination of Me3SiCl, concurrent with [N═PCl3]− formation, constitutes the rate‐limiting step. Accordingly, this type of polymerization can be described as a chloride‐catalyzed cationic process. These findings provide a detailed mechanistic understanding of poly(dichlorophosphazene) formation and offer a basis for optimizing reaction conditions to achieve controlled polymerization.
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BibTeX
@article{knuth2026insights,
title = {{New Insights into Poly(Dichlorophosphazene) Synthesis via Me3Si─N═PCl3 Polymerization: An Experimental and Theoretical Study}},
author = {Cornelius Knuth and Paul Strasser and Carmen Hoth and Joerg Harloff and Thomas Eickner and Ian Teasdale and Axel Schulz},
journal = {Chemistry (Weinheim an Der Bergstrasse, Germany)},
year = {2026},
month = jul,
doi = {10.1002/chem.71399},
url = {https://doi.org/10.1002/chem.71399},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - New Insights into Poly(Dichlorophosphazene) Synthesis via Me3Si─N═PCl3 Polymerization: An Experimental and Theoretical Study
AU - Cornelius Knuth
AU - Paul Strasser
AU - Carmen Hoth
AU - Joerg Harloff
AU - Thomas Eickner
AU - Ian Teasdale
AU - Axel Schulz
PY - 2026
DA - 2026/07/31
JO - Chemistry (Weinheim an Der Bergstrasse, Germany)
DO - 10.1002/chem.71399
UR - https://doi.org/10.1002/chem.71399
AB - Polyphosphazenes are a unique class of polymers, notable for their versatile functionalization and distinctive properties arising from their alternating phosphorus–nitrogen backbone. However, the synthesis of their primary precursor, poly(dichlorophosphazene) ([NPCl2] n ), is notoriously delicate and poorly understood, limiting broader adoption. Herein, we reinvestigate the controlled polymerization of Me3Si─N═PCl3 using quantum mechanical calculations to elucidate its underlying mechanism. Guided by these insights, we optimized the experimental conditions and achieved significantly higher molecular weights than previously reported for this polymerization route. Polymerization occurs at ambient temperature only upon addition of a cationic initiator, such as Ph3PCl2, yielding [NPCl2] n chains of varying lengths. Experiments and DFT calculations indicate that initiation proceeds via three key steps: (i) dissociation of Ph3PCl2 into [Ph3PCl]+ and Cl− ions, dependent on the reaction medium; (ii) nucleophilic attack of Cl− on Me3Si─N═PCl3, producing [N═PCl3]− and eliminating Me3SiCl; (iii) reaction of [N═PCl3]− with [Ph3PCl]+ to form Ph3P─NPCl4, which dissociates to generate additional reactive species, propagating chain growth. The elimination of Me3SiCl, concurrent with [N═PCl3]− formation, constitutes the rate‐limiting step. Accordingly, this type of polymerization can be described as a chloride‐catalyzed cationic process. These findings provide a detailed mechanistic understanding of poly(dichlorophosphazene) formation and offer a basis for optimizing reaction conditions to achieve controlled polymerization.
SN - 0947-6539
SN - 1521-3765
ER -