Hexachlorophosphazene has a  core with six equivalent P–N bonds, for which the adjacent P–N distances are 157 pm. This is characteristically shorter than the ca. 177 pm P–N bonds in the valence saturated phosphazane analogues.
The molecule possesses D symmetry, and each phosphorus center is tetrahedral with a Cl–P–Cl angle of 101°.
The  ring in hexachlorophosphazene deviates from planarity and is slightly ruffled (see chair conformation). By contrast, the  ring in the related hexafluorophosphazene species is completely planar.