A p-Xylene Clathrate of Tris(1,8-naphthalenedioxy)cyclotriphosphazene. X-Ray Crystal and Molecular Structure

Tris(1,8-naphthalenedioxy)cyclotriphosphazene (III) forms a clathrate inclusion adduct with p-xylene. An X-ray single-crystal study has shown that the p-xylene molecules are physically trapped in a fixed position within channels that penetrate the lattice. The naphthalenedioxy side groups of the host molecules (III) are bent at the oxygen atoms in such a way that strong host-host interactions stabilize the channel structure. The unit cell is triclinic, with space group P1 and with a = 8.206 (17) Å, b = 14.747 (25) Å, c = 13.318 (23) Å, α = 101.97 (7)°, β = 90.77 (7)°, 7 = 109.13 (5)°, and Z = two host molecules and one p-xylene. The structure was solved by symbolic addition methods, and refinement to an R index of 0.058 was accomplished by Fourier and least-squares techniques. The important mean bond angles and distances within the host molecules are P-N = 1.57 Å, P-O = 1.59 Å, N-P-N = 117.9°, P-N-P = 122.1°, N-P-O = 106.7-110.9°, and O-P-O = 102.2°. The phosphazene ring is puckered in a boat conformation.