The crystal structure of tris(2,2'-dioxybiphenyl)cyclotriphosphazene (II) has been determined by three-dimensional Patterson, Fourier, and difference syntheses, and refinement to an R index of 0.068 was accomplished by difference-Fourier and least-squares techniques. o The crystals are monoclinic with the space group C2/c, and with a = 15.377 (2), b = 10.810 (1), c = 20.152 (7) Å, β = 108.88 (0.02)°, Z = 4. The cyclotriphosphazene ring has a slight boat conformation. Two of the biphenyldioxyphosphole units are twisted propellor-like at 43° in one direction while the third is twisted at 52° in the opposite direction. The P-N bond distances are 1.568 (7), 1.582 (6), and 1.566 (4) Å the N-P-N angles are 118.6 (0.3) and 118.3 (0.2)°; the P-N-P angles are 120.8 (0.3) and 121.2 (0.2)°; and the O-P-O angles are 103.0 (0.2) and 102.4 (0.3)°. The asymmetry of twist of the side group units is discussed and reasons are suggested for the failure of this compound to polymerize or form molecular inclusion adducts.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry