Conformational stability and force field of short-chain linear chlorophosphazenes: MNDO calculations, {sup 31}P NMR, vibrational spectra, and normal coordinate analyses of Cl{sub 3}PN(PCl{sub 2}N){sub n}P(O)Cl{sub 2} and [Cl{sub 3}PN(PCl{sub 2}N){sub n}PCl{sub 3}][PCl{sub 6}] (n = 1,2)
Journal Article
·
· Journal of Physical Chemistry
- Universite des Sciences et Technologies de Lille, Villeneuve d`Ascq (France)
The Raman spectra of Cl{sub 3}PN(PCl{sub 2}N){pi}P(O)Cl{sub 2} and [Cl{sub 3}PN(PCl{sub 2}N){pi}PCl{sub 3}]{sup +}PCl{sub 6}{sup {minus}} (n = 1,2) were recorded in the solid and liquid states at different temperatures. The qualitative depolarization ratios were obtained in the liquid phase. A {sup 31}P NMR study for the molecular compounds showed a coalescence phenomenon near 220 K. The potential energy around the PN bonds for the Cl{sub 3}PN(PCl{sub 2}N)P(O)Cl{sub 2} molecule and [Cl{sub 3}PN(PCl{sub 2}N){sub 2}PCl{sub 3}]{sup +} cation are derived from MNDO (modified neglect of diatomic overlap) calculations. The stable conformations are found to be trans-cis for Cl{sub 3}PN(PCl{sub 2}N)P(O)Cl{sub 2} and [Cl{sub 3}PN(PCl{sub 2}N){sub 2}PCl{sub 3}]{sup +}. The calculated structural parameters agree well with the X-ray experimental data. The frequencies obtained by normal coordinate analysis are in good agreement with the observed ones. The MNDO calculation of the harmonic force field is in reasonable agreement with the experimental values. The force constant values assigned to torsional modes around the PN bonds correspond to low barriers for the internal rotations. The easy internal rotation around the P-N and P{double_bond}N bonds can explain the flexibility of the phosphazene backbone and the elastomeric properties of the phosphazene polymers. 46 refs., 6 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 458802
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 22 Vol. 96; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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