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Novel trispirocyclotriphosphazenes with oxaphosphorine rings (DOP-PZs) were successfully synthesized by an Appel reaction with phosphoramide, which was prepared from ammonia and 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derived from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, generally abbreviated as DOPO. The resulting DOP-PZs were characterized by 1H, 13C{1H}, and 31P{1H} nuclear magnetic resonance spectroscopy and time-of-flight mass spectrometry and shown to consist of cis-trans isomers. Moreover, the crystal and molecular structures of the DOP-PZs were determined by X-ray diffraction; cis- and trans-DOP-PZs (C36H24N3O3P3, M = 639.49 g/mol) were refined to final R1 values of 0.0260 and 0.0463, respectively, with the SHELXL refinement package using least-squares minimization. The crystal of cis-DOP-PZ is trigonal in space group R3c and the following cell constants: a = 19.5984(5) Å, c = 13.2754(4) Å, V = 4415.9(3) Å3, Z = 6, and Flack parameter = 0.038(8). In contrast, trans-DOP-PZ is monoclinic in space group P21/c and the following cell constants: a = 9.98647(18) Å, b = 24.1737(4) Å, c = 12.8472(2) Å, β = 112.649(8)°, V = 2862.26(18) Å3, and Z = 4. The molecular structures of these DOP-PZs were compared with those of other trispirocyclotriphosphazenes. In addition, the DOP-PZs showed high thermal stability up to 400 °C, with dielectric constants of 2.76-2.77 and dissipation factors of 0.0017-0.0031 at 10 GHz.

Citation

Yuji Tada, Atsushi Sunada, Riki Watanabe, Makoto Kanazawa, Keiichiro Utsumi. Synthesis of Trispirocyclotriphosphazenes with Oxaphosphorine Rings and Their Crystal and Molecular Structures. Inorganic chemistry. 2021 Apr 05;60(7):5014-5020


PMID: 33733777

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