1,1,1,3,3,3-Hexakis(dimethylamino)-1λ5, 3λ5-diphosphazenium Fluoride

Abstract

[137334-99-7] C12H36FN7P2 (MW 359.49) InChI = 1S/C12H36N7P2.FH/c1-14(2)20(15(3)4,16(5)6)13-21(17(7)8,18(9)10)19(11)12;/h1-12H3;1H/q+1;/p-1 InChIKey = IRKKKQOVDCZGGC-UHFFFAOYSA-M (anhydrous stable organic fluoride salt; source of homogeneous, extremely basic solutions of ‘naked’ fluoride ions of unprecedented reactivity and selectivity in E2 elimination reactions;1 readily cleaves CSi bonds, generating extremely reactive ‘naked’ carbanions1) Alternate Name: P2-F. Physical Data: mp ca. 152 °C (dec); d 1.193 g cm−3. Solubility: very sol benzene, fluorobenzene (with partial deactivation); sol with deactivation in protic solvents, acetonitrile, DMSO; sparingly sol toluene, dioxane, HMPA, THF; reacts rapidly with partially halogenated alkanes and slowly with CCl4. Form Supplied in: commercially available as a 0.5 M solution in benzene. Preparative Methods: a solution of 1,1,1,3,3,3-hexakis(dimethylamino)-1λ5,3λ5-diphosphazenium tetrafluoroborate1 (12.8 g, 30.0 mmol) in anhydrous MeOH (20 mL) is treated with a solution of KF (1.83 g, 31.5 mmol, dried for 12 h at 240 °C in a high vacuum) in cold MeOH (25 mL) under N2 and stirred vigorously for 10 min. The KBF4 is removed by suction. The flask is then equipped with a glass-covered stirring bar, the solution concentrated in vacuo at 40–50 °C bath temperature, purged with N2, and anhydrous i-PrOH (5 mL) is added. This sequence is repeated twice. The flask is then fitted to the cold trap of a (diffusion pump) vacuum apparatus, connected by a 10-mm flow cross-section stop-cock. The solution is concentrated in vacuo with stirring, the bath temperature being brought to 80 °C within 1 h and kept for 1 h at 80 °C and 1 h at 100 °C. For the following operations, rigorous exclusion of moisture (glove box) is essential. The completely solidified product is scratched from the surface of the flask and dried for 1 h at 120 °C. The product is slurried in absolute THF (20 mL), larger lumps are crushed with a pestle, the crystals filtered off with a D4 glass suction filter, washed with absolute THF (15 mL) and dried in a high vacuum, providing 9.7 g (90%) of colorless crystals, 98–99% in ‘naked’ fluoride by titration; ca. 1% of inorganic material can be removed by filtration of the benzene solution. Analysis of Reagent Purity: 1H NMR (benzene-d6) δ 2.60; by titration in benzene with solid HPF6 salt of 1,8-bis(dimethylamino)naphthalene, with triphenylmethane as indicator. Handling, Storage, and Precautions: store and handle so as to rigorously exclude moisture. It is thermally stable up to ca. 100 °C and insensitive to dry oxygen.