SYNTHESIS AND STRUCTURE OF SMALL-MOLECULE CYCLIC PHOSPHAZENES BEARING ORTHO-SUBSTITUTED ARYLOXY AND PHENOXY SUBSTITUENTS

A series of cyclic trimeric and tetrameric phosphazenes with ortho-substituted aryloxy side groups have been synthesized. The ortho substituents are methyl and phenyl groups. These compounds are structural models for the corresponding linear high-polymeric phosphazenes. X-ray structural analysis of the cyclic tetrameric species [NP(OC6H4CH3-2)2]4 (3), [NP(OC6H4C6-H5-s)2]4 (4), and [NP(OC6H5)2]4 (5) are reported. Crystals of 3 are triclinic with space group P1BAR, with a = 11.494 (3) angstrom, b = 12.348 (2) angstrom, c = 30.181 (5) angstrom, alpha = 80.88 (1)-degrees beta = 88.19 (2)-degrees, gamma = 71.23 (1)-degrees V = 4003.6 angstrom3, and Z = 3. Crystals of 4 are orthorhombic with space group Pna2(1), with a = 25.177 (2) angstrom, b = 20.472 (3) angstrom, c = 17.256 (3) angstrom, V = 8894.1 angstrom3, and Z = 4. Finally, crystals of 5 are triclinic with space group P1BAR, with a = 11.514 (2) angstrom, b = 11.567 (2) angstrom, c = 17.761 (1) angstrom, alpha = 79.21 (1)-degrees, beta = 79.87 (1)-degrees, gamma = 81.21 (1)-degrees, V = 2269.8 angstrom3, and Z = 2.