Tetrameric Fluorophosphazene, (NPF₂)₄, Planar or Puckered?

Abstract

The results obtained in a comprehensive experimental study on the redetermination of the structure of N(4)P(4)F(8) with single-crystal X-ray diffraction, gas electron diffraction (GED), and differential scanning calorimetry (DSC) establish clearly that, in contrast to the previous report, the eight-membered heterocycle is not planar. Above the phase transition temperature of -74 degrees C, the ring appears pseudoplanar. However, the N(4)P(4) ring is disordered and is puckered above the phase transition when the disorder is modeled correctly. Below the phase transition the ring clearly resembles that of the saddle (K form) of N(4)P(4)Cl(8). The unit cell of the low-temperature phase is derived from that of the higher temperature phase by doubling the c-axis and removing one-half of the symmetry elements. Full structure optimizations were performed at the HF/6-31G and B3LYP/6-31G levels and fully support the experimental diffraction data.

P4N4F7O−—the isoelectronic counterpart of P4N4F8

“…The structure of the anion is compared with that of the isoelectronic neutral fluorophosphazene N 4 P 4 F 8 . The results recently obtained by the groups of Shreeve, Krebs, Oberhammer and our group [6] in a comprehensive experimental study on the redetermination of N 4 P 4 F 8 with single crystal X-ray diffraction, gas electron diffraction (GED) and differential scanning calorimetry (DSC) established, that in contrast to previous reports, the eight-membered heterocycle is not planar.…”

Spectrum of Exfoliable 1D van der Waals Molecular Wires and Their Electronic Properties

“…We choose representative materials from the families and simple wire prototypes to evaluate using density functional theory calculations. Materials from the common structural families SbSeI, TaTlSe 3 , and HfI 3 were selected in addition to PdBr 2 , PNF 2 , , and GePdS 3 , which display simple, spatially separated wire compositions. We also perform calculations on materials that exhibit wire-like character but insufficient spacing between wires to satisfy the screening criteria of Cheon et al .…”

Analysis and calculation of the 31P and 19F NMR spectra of hexafluorocyclotriphosphazene

“…This result is not trivial since experimental data for the majority of cyclophosphazenes show distortion from the highest possible symmetry and the next homologue, tetrameric F 2 PN 4 , even has a fluxional structure. 50 …”