Theoretical Study of the Linear Short-Chain Phosphazene-Na+ Complexes

Abdellatif, M. L.; Maouche, Boubekeur; Belmiloud, Yamina; Triaki, Nabila; Brahimi, Méziane

doi:10.2174/1874199100903010026

Cited by 4 publications

(3 citation statements)

References 39 publications

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“…Aligning with the work reported by Chaplin et al, a similar interaction has been described in short linear chlorophosphazenes . These interactions can also correlate with the density functional theory (DFT) studies of bonding environments described for the cyclic and polymeric models in stage 2. − …”

Section: Introductionmentioning

confidence: 82%

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl₃P═NH: A Theoretical Study via Quantum Mechanical Calculations

Salmon,

Xue,

Gogonea

2023

Inorg. Chem.

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Although the synthesis of chlorophosphazene polymers has been explored for more than 100 years, the shortest yet most illusive monomer, Cl 3 P�NH, has never been isolated and fully characterized.Here we investigate the formation of Cl 3 P�NH from PCl 5 and NH 3 in chlorobenzene through quantum mechanical calculations. The potential energy surface was mapped using the MP2 Hamiltonian in conjunction with Dunning's correlation-consistent basis sets (aug-cc-pVXZ, where X = D and T). Along with HOMO/LUMO frontier molecular orbitals and natural bond orbital analyses, we found that instead of following the S N 1 path proposed in the literature, the reaction proceeds via an addition− elimination mechanism. Our results also indicate that due to the low-lying stable intermediates (IM), most steps are exothermic such that the production of Cl 3 P�NH•2HCl can be completed once the energy barrier for the formation of [PCl 4 -NH 3 ] + Cl − is overcome. Therefore, our theoretical work might explain the challenges in isolating any of the IMs in a typical chlorophosphazene reaction in chlorobenzene.

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Section: Introductionmentioning

confidence: 82%

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl₃P═NH: A Theoretical Study via Quantum Mechanical Calculations

Salmon,

Xue,

Gogonea

2023

Inorg. Chem.

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“…In this series of cyclic phosphazenes (NPX 2 ) 3 with X = H, Br, Cl and F, all identical PN bonds lengths obtained is a sign of aromaticity in this compounds. Used Quantum chemical calculations in order to find the effect of substitution halogens atoms in PN bonds; Abdellatif et al [60] have reported that the PN bond lengths in short linear phosphazenes decrease with increasing the electronegativity of (R 3 PNH, R 3 PNF and R 3 PNOH with R=H, F). Sabzyan et al have reported that the PN bond lengths in the cyclic phosphazenes decrease with increasing the electronegativity of the halogen substituent on the phosphorus atom [57].…”

Section: Structural Datamentioning

confidence: 99%

Structural Data, Linear and Nonlinear Optical Properties of Some Cyclic Phosphazenes: A Theoretical Investigation

Hadji

Rahmouni²

2015

J. Appl. Sol. Chem. Model.

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We report ab initio and DFT calculation of structural data, dipole moment, diagonal vibrational and electronic contributions to polarizability, vibrational and electronic contributions to first hyperpolarizability of some cyclic phosphazenes. The electronic structure of substituted cyclic phosphazenes has been investigated using Hartree-Fock and density functional theory. The vibrational and electronic contributions to polarizabilities and first hyperpolarizability of these molecules were calculated with HF method, and different DFT levels used the traditional B3LYP and PBE functional and the long-range corrected functional like Coulomb-attenuating method CAM-B3LYP, LC-BLYP and wB97XD used different basis sets. These cyclic phosphazenes adopts a planar structure. The study reveals that the cyclic phosphazenes derivatives have large vibrational contribution to static first hyperpolarizability values. The results obtained from this work will provide into the electronic properties of this important class of inorganic polymers.

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“…Previous computational efforts have primarily focused on analyzing the experimentally proven products in Scheme , , assuming the validity of the proposed S N 1 mechanism. Although computational analysis of the discrete polymer, cyclic compounds, and monomer has been performed, ,,− , the role of [PCl 2 N] 3 in the ROP and RR equilibrium polymerization has never been systematically addressed using QM calculation methods. Here, we investigate the ROP mechanism starting with two and three [PCl 2 N] 3 rings by systematically mapping reaction pathways on the potential energy surface (PES), without assuming a predetermined mechanism.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Mechanistic Analysis of the Ring-Opening Polymerization of [PCl₂N]₃ Using Quantum Mechanical Calculations

Xue,

Salmon,

Ramlo

et al. 2024

Macromolecules

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The most popular method to synthesize polychlorophosphazenes, the parent of a prominent class of inorganic polymers, is the ring-opening polymerization (ROP) of [PCl 2 N] 3 . In contrast to the accepted (S N 1-initiated) ROP mechanism that begins with heterolytic P−Cl bond cleavage in [PCl 2 N] 3 , our quantum mechanical (QM) calculations suggest that the ROP can proceed through a S N 2-like route in which one [PCl 2 N] 3 can be attacked by a neighboring [PCl 2 N] 3 and hence transform through a four-center transition state (4C PNPCl TS), yielding a cyclic chlorophosphazene with a linear tail, termed a "tadpole". Meanwhile, two [PCl 2 N] 3 molecules can morph into [PCl 2 N] 6 (RR expansion) through a different four-center transition state (4C PNPN TS) without the assistance of a bridging chlorine. As the activation energy of these processes follows the trend tadpole backbite < chain branching < ROP initiation ≤ RR initiation = RR expansion < chain propagation (all within 241.2 ± 16 kJ/mol), the ROP and RR mechanisms compete toward product formation. Not only does our pioneering QM calculations unveil the pivotal role of the bridging chlorine in the S N 2 mechanism, it also explains its effect on reactivity of [PCl 2 N] 3 species, underscoring the significance of halogen substituents in modulating polymerization. By comprehensively examining the ROP, RR, linear propagation, and ring closure processes, we attempt to resolve long-standing queries in chlorophosphazene research, elucidating the wide variability in reaction pot products and the necessity of halogen substituents in specific processes. Thus, this work characterizes a variety of four-center transition states for the first time and introduces a novel mechanistic process for polymerization. Finally, our work provides an explanation of the existence of the chlorinated tadpole.

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Theoretical Study of the Linear Short-Chain Phosphazene-Na+ Complexes

Cited by 4 publications

References 39 publications

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl₃P═NH: A Theoretical Study via Quantum Mechanical Calculations

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl₃P═NH: A Theoretical Study via Quantum Mechanical Calculations

Structural Data, Linear and Nonlinear Optical Properties of Some Cyclic Phosphazenes: A Theoretical Investigation

Comprehensive Mechanistic Analysis of the Ring-Opening Polymerization of [PCl₂N]₃ Using Quantum Mechanical Calculations

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Theoretical Study of the Linear Short-Chain Phosphazene-Na+ Complexes

Cited by 4 publications

References 39 publications

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl3P═NH: A Theoretical Study via Quantum Mechanical Calculations

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl3P═NH: A Theoretical Study via Quantum Mechanical Calculations

Structural Data, Linear and Nonlinear Optical Properties of Some Cyclic Phosphazenes: A Theoretical Investigation

Comprehensive Mechanistic Analysis of the Ring-Opening Polymerization of [PCl2N]3 Using Quantum Mechanical Calculations

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Formation Mechanism of the Unsubstituted Chlorophosphazene Cl₃P═NH: A Theoretical Study via Quantum Mechanical Calculations

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl₃P═NH: A Theoretical Study via Quantum Mechanical Calculations

Comprehensive Mechanistic Analysis of the Ring-Opening Polymerization of [PCl₂N]₃ Using Quantum Mechanical Calculations