The crystal structure of molecular inclusion compounds of tris(o-phenylenedioxy)phosphonitrile trimer

Abstract

The crystal structures of the benzene and bromobenzene inclusion compounds of tris(o-phenylenedioxy)phosphonitrile timer have been determined using three-dimensional methods. The compounds are isomorphous, with a hexagonal unit cell containing two phosphonitrilic host molecules and approximately one included guest molecule. The centres of the phosphonitrilic rings are located on the special positions (1/3, 2/3, z) and (2/3, 1/3, z+ 1/2) of space group P6₃. The structural arrangement of the host molecules forms a channel along the c axis, and the guest molecules are in disordered positions within this channel.

Least-squares refinement of the host molecule parameters only, employing anisotropic correction factors, led to final R values of 0·073 and 0·083 for the benzene and bromobenzene compounds, respectively. The phosphonitrilic ring is planar, and the average bond distance in the ring is 1·575 ± 0·002 Å. The O–P–O angle of 97° is smaller than the equivalent angle in simply substituted phosphonitrilic trimers, but is close to the angle of 99° reported for methyl ethylene phosphate.