The synthesis of [NP(CH2SiMe3)2]3 has been achieved in almost quantitative yield via the reaction of Me3SiCH2Li with (NPF2)3 in tetrahydrofuran at 40 °C, followed by addition of a proton source. Treatment of [NP(CH2SiMe3)2]3 with nBu4N+F− gave (NPMe2)3 in 60% yield. Partially substituted trimers of the formula N3P3Fx(CH2SiMe3)6-x, where x = 2 and 4, were also prepared. The interaction of (NPF2)3 with Me3SiCH2Li involves a metal-hydrogen exchange side reaction to generate species such as N3P3-(CH2SiMe3)5(CHSiMe3)−Li+, hence the need for subsequent protonation. Attempts to replace the fluorine atoms in gem-N3P3F4(CH2SiMe3)2 by treatment with NaOCH2CF3 led also to C-Si bond cleavage to generate gem-N3P3(OCH2CF3)4Me2. No C-Si bond cleavage occurred during the attempted preparation of gem-N3P3(OCH2CF3)2(CH2SiMe3)4, and none was detected when [NP(CH2SiMe3)2]3 was treated with NaOCH2CF3. The structure of [NP(CH2SiMe3)2]3 has been determined by single-crystal X-ray diffraction methods. Crystals were monoclinic with a P21/n space group, with a = 11.012 (2) A, b = 19.851 (5) Å, c = 19.554 (8) Å, β = 90.51 (2)°, V = 4309.3 Å3, and Z = 4. A comparison is made with other alkyl- and (alkylsilyl)cyclo-triphosphazenes.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry