The electronic structure of planar phosphazene rings

Abstract

Using a standard ab initio method, the electronic structure and optimal geometries of cyclo-(NPX 2) n ( n=2, 3, 4 and X=H, F, Cl) have been investigated using the DZP basis set. The out-of-plane π bonds as well as the in-plane π′ bonds in phosphazenes are dominated by p orbitals, although the bonding interaction between p orbitals on N atoms and d orbitals on P atoms is symmetrically forbidden in rings of D nh symmetry with odd n only. In-plane π′ and σ bonds in cyclic planar phosphazenes can be distinguished using Mulliken population analysis of cylindrical atomic orbitals. The d functions on P atoms do not correspond to their d orbitals and can be explained as polarization functions only.