Solid-state nuclear magnetic resonance investigations on chlorocyclophosphazenes

The present study deals with solid-state nuclear magnetic resonance (NMR) investigations on hexachlorocyclotriphosphazene (N3P3Cl6) and T and K form of octachlorocyclotetraphosphazene (N4P4Cl8). Using 31P NMR we have recorded spectra of different magic-angle spinning (MAS) frequencies and static powder spectra. By means of the analysis of spinning sideband intensities the isotropic chemical shifts and the principal values of the chemical shift tensor could be determined. Because of the interactions between phosphorus and the neighbouring chlorine nuclei in the MAS spectra of N3P3Cl6 and N4P4Cl8 more lines were found to exist than was expected with regard to the isotropic chemical shift values according to the crystallographic phosphorus positions. To support this evidence solid-state spectra of the geminally disubstituted compound 2,2,4,4-tetrachloro-6,6-bisthiophenylcyclotriphosphazene [N3P3Cl4(SPh)2] were used. In addition, by means of the individual gauched localized orbitals (IGLO) method 31P NMR chemical shifts, principal values and the orientation of the principal axes of the shielding tensor were calculated for the chlorocyclophosphazenes.