Nuclear quadrupole resonance of 35Cl in phosphonitrilic chloride tetramer

Abstract

The ³⁵Cl nuclear quadrupole resonance spectra of the two crystalline forms (K and T) of phosphonitrilic chloride tetramer, (PNCl₂)₄, have been recorded between 77°K and the melting-point. The molecular point symmetries of 4 in the K-form and 1 in the T are confirmed, although the latter appears to approach 2/m symmetry as the melting point is reached. A transition temperature in which the K-form goes to the T has been observed at 63±1.5°C. The large frequency difference between axial and equatorial chlorine nuclei in the 1-molecule is tentatively ascribed to differences in π-character of the P—Cl bonds.