Syntheses and Structures of Cyclic and Short-Chain Linear Phosphazenes Bearing 4-Phenylphenoxy Side Groups

A series of cyclic and short-chain linear phosphazenes bearing the 4-phenylphenoxy side group has been synthesized. These compounds are models for the corresponding linear high polymer. The X-ray structures of [NP(O-C₆H₄-C₆H₅-p)₂]₃ (1), [NP(O-C₆H₄-C₆H₅-p)₂]₄ (2), and OP₃N₂(O-C₆H₄-C₆H₅-p)₇ (6) are reported. Compound 6 represents the first three-phosphorus linear oligomeric phosphazene-bearing aryloxy side group to be described. The molecular structure of 6 showed that the linear phosphazene skeleton assumes a distorted cis-trans conformation. Crystals of 1 are monoclinic with space group P2₁/c with a = 23.296 (6) Å, b = 7.762 (4) Å, c = 34.666 (7) Å, 0 = 90.14 (2)°, V = 6268.4 ų, and Z = 4. Crystals of 2 are triclinic of space group P1 with a = 10.462 Å, b = 16.433 Å, c = 23.326 Å, a = 94.25 (2)°, 0 = 91.03 (3)°, y = 103.59 (3)°, V = 3883.9 ų, and Z = 2. Finally, crystals of 6 are monoclinic with space group P₁/n with a = 10.413 (9) Å, b = 23.425 (9) Å, c = 36.359 (12) Å, β = 96.27 (6)°, V = 8815.77 ų 6, and Z = 4.