Dimethylamino tetrafluorophosphorane

Constriction sufficient to allow passage of syringe needle and for easy sealing 

The whole system is evacuated, flame-heated and left pumping for a period of about 2 hours before the experiment is started. The vacuum line is closed to the pump when the pressure remains constant at about 0.05 torr or less and phosphorus pentafluoride is condensed directly into the trap cooled to liquid 

The experiment can be shortened somewhat if the reaction tube is allowed to warm from -196° to room temperature over a 1-hour period. The glass tube should be enclosed in a thick walled cylindrical metal container, and placed in a hood, using explosion-proof shielding. We have, however, had no cases in which the tube has exploded. After completion of the reaction, the tube is opened and the contents are decanted directly into the distillation flask. A lower yield is obtained by this procedure because of the formation of ionic products. 

The fluoro phosphoranes may be stored in glass bottles for brief periods, but attack is appreciable, and the use of Teflon or stainless steel containers is preferable. 

At -90° two distinct fluorine atom environments are observed, the structure being interpreted in terms of a trigonal bipyramid in which two fluorine atoms occupy axial sites. Two F resonances are observed, an axial resonance, consisting of a doublet of triplets, due to P and F coupling, and an equatorial resonance, consisting of a doublet of triplets due to P and F coupling. 

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Dimethylamino)tetrafluorophosphorane is a colorless liquid that fumes when exposed to moist air. Melting points of-80 and -78°, and boiling points of 60 and 63.7°, have been reported. The vapor pressure may be expressed by the equation... 

The apparatus and procedure employed for the preparation of (diethylamino)-tetrafluorophosphorane are identical to that described for the preparation of (dimethylamino)tetrafluorophosphorane (Sec. B). All of the precautions described in preparation B should be observed. Phosphorus pentafluoride (31.6 g, 0.25 mole) and (diethylamino)trimethylsilane (A, A -diethyl-l,l,l-trimethyl-silylamine) (0.25 mole, 36.3 g) are used. 

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