Phosphorus pentafluoride

Phosphorus pentafluoride PF will readily accept an electron pair from a fluoride ion F to form the stable hexafluorophosphate(V) anion PF C. This ion is isoelectronic with SF. and neither SF nor PF show any notable tendency to accept further electron pairs, though there is some evidence for the existence of an SF ion. 

Arsenic forms only the pentafluoride AsFj, a colourless liquid, b.p. 326 K. This resembles phosphorus pentafluoride. 

Hall and Steuck polymerized 2 with a variety of Lewis and Bronsted acids or oxonium salts. The best conditions for the polymerization proved to be the use of phosphorus pentafluoride in methylene chloride solution at -78 °C. Yields of methanol-insoluble polymers ranging from 68 to 84% were obtained with inherent viscosities of 0.26—0.33 dl/g. Lower or higher temperatures gave lower yields. Tetra-hydrofuran as solvent at —78 °C gave 68-92% yields of materials having inherent viscosities of 0.12-0.14 dl/g. No incorporation of tetrahydrofuran into the polymer occurred. 

Polymerization of 4-bromo-6,8-dioxabicyclo[3.2.1 ]octane 2 7 in dichloromethane solution at —78 °C with phosphorus pentafluoride as initiator gave a 60% yield of polymer having an inherent viscosity of 0.10 dl/g1. Although it is not described explicitly, the monomer used seems to be a mixture of the stereoisomers, 7 7a and 17b, in which the bromine atom is oriented trans and cis, respectively, to the five-membered ring of the bicyclic structure. Recently, the present authors found that pure 17b was very reluctant to polymerize under similar conditions. This is understandable in terms of a smaller enthalpy change from 17b to its polymer compared with that for 17a. In the monomeric states, 17b is less strained than 17a on account of the equatorial orientation of the bromine atom in the former, whereas in the polymeric states, the polymer from 17b is energetically less stable than that from 17a, because the former takes a conformation in which the bromine atom occupies the axial positioa Its flipped conformation would be even more unstable, because the stabilization by the anomeric effect is lost, in addition to the axial orientation of the methylene group. 

Attempted polymerization of ds-7,9 dioxabicyclo[4.3.0]nonane 43 with phosphorus pentafluoride as initiator at temperatures ranging from -25 to 0 °C provided only a cyclic dimer 44 in high yield35. Under similar conditions trans-7,9-dioxabicyclo-[4.3.0]nonane 45 polymerized almost instantly to polymer 46 with number average molecular weight of several thousands, along with a small amount of a cyclic dimer 47. 

The reactions of phosphorus pentachloride and diphenyltrichloro-phosphorane with amines and related compounds are reported in Chapter 9. The n.m.r. spectra of phosphine-phosphorus pentafluoride adducts have been described (see Chapter 11 for details). 

Phosphorus pentafluoride Phosphorus trifluoride F T Steel, nickel, Monel and Pyrex for dry gas. For moist gas hard rubber and paraffin wax Steel, nickel, Monel and the more noble metals and Pyrex for dry gas... 

Interaction of the fluorides to produce chlorotetrafluorophosphorane [1] is uncontrollably violent even at — 196°C [2], An improved method of making the phos-phorane from phosphorus pentafluoride and boron trichloride is detailed [2],... 

Phosphorus pentafluoride Phosphorus pentasulfide Phosphorus pentoxide Phosphorus, red Phosphorus tribromide Phosphorus bichloride Water or steam Air, alcohols, water Formic acid, HF, inorganic bases, metals, oxidants, water Organic materials Potassium, ruthenium tetroxide, sodium, water Acetic acid, aluminum, chromyl dichloride, dimethylsulfoxide, hydroxylamine, lead dioxide, nitric acid, nitrous acid, organic matter, potassium, sodium water... 

Phosphorus pentachloride, 79 40, 42-44 end use of chlorine, 6 135t sodium reactions with, 22 766 Phosphorus pentafluoride, 79 33 Phosphorus pentahalides, 79 31-33 Phosphorus pentoxide, 79 49, 69. See also Phosphorus(V) oxides as cellulose solvent, 77 272 in hydrogen fluoride manufacture, 74 11 vapor of, 79 49... 

As far as the polymerisations of DCA other than DXL by non-protonic initiators are concerned, Kops and Spanggaard [11] favour the ring expansion mechanism for the dimerisation and polymerisation of the cis- and tnms-7,9-dioxabicyclo[4.3.0] nonanes by phosphorus pentafluoride or triethyloxonium hexachloroantimonate, although they have not obtained any definitive evidence for it. 

Stability calculations on the phosphoranes (79) have appeared.71 Various potential functions for phosphorus pentafluoride (73 n = 0) have been reported.72 73 An e.s.r. study of y-irradiated phosphorus pentachloride has been published.74 New thermochemical data on phosphorus pentabromide have appeared.76... 

Preparation of Phosphoranes by Exchange Methods.—A convenient procedure has been developed for the one-step synthesis of chlorotetrafluorophosphorane (93).80 The phosphorane (94) has been prepared as shown.81 Ring opening of the disilacyclo-butane (95) by phosphorus pentafluoride affords the bisphosphorane (96), characterized by its spectra.82... 

Miscellaneous.—Hydridofluorophosphates have been prepared for the first time, and the anion (129) has been found to have an octahedral structure, with hydrogens trans.116 Phosphorus pentafluoride forms an adduct with biscyclopentadienyl titanium difluoride.116 The phosphorane (130) has been prepared as shown.117... 

Nonmetals, such as sulfur, phosphorus and carbon (amorphous) inflame in fluorine forming their corresponding fluoro compounds, such as sulfur hexafluoride (SFe), phosphorus pentafluoride (PF5), and carbon tetrafluoride (CF4). 

Phosphorus pentafluoride is a catalyst in ionic polymerization reactions. 

Phosphorus pentafluoride may be prepared by several methods, among which are ... 

Phosphorus pentafluoride hydrolyzes in water, the products formed depend on the reaction conditions. When exposed to moisture it forms phosphorus oxyfluoride ... 

Phosphorus pentafluoride is a highly toxic gas. Inhalation can cause severe irritation of mucous membrane and pulmonary edema. It is corrosive to skin and can damage eyes. 

---