Selenium Hexafluoride SeFs

Selenium hexafluoride, SeF m.p. — 39°C, sublimes —47°C. Formed (with Sc2Fio) from Se and F2- Chemically fairly inert. 

CHEMICAL PROPERTIES stable under ordinary conditions of use and storage hydrolyzes slowly in water to telluric acid (H606Te) more quickly hydrolyzed by aqueous potassium hydroxide when pure, does not attack glass corrosive to mercury not as chemically inert as sulfur hexafluoride (SF(,) and selenium hexafluoride (SeFs) because the maximum covalence of tellurium is greater than six FP (NA) LFLZUFL(NA) AT(NA) HC(NA) HF(-1318.0 kJ/mol gas at 25 C) Tc (83 C, 181.4 ). 

Selenium hexafluoride, SeFg, the only clearly defined hexahalide, is formed by reaction of fluorine with molten selenium, It is more reactive than the corresponding sulfur compound, SFs, undergoing slow hydrolysis. Selenium forms tetrahalides with fluorine, chlorine, and bromine, and dihalides with chlorine and bromine. However, other halides can be found in complexes, e.g,. treatment of the pyridine complex of SeF/i in ether solution with HBr yields (py)2SeBrc Selenium tetrafluoride also forms complexes with metal fluorides, giving MSeF complexes with the alkali metals. 

Methylselenol CHaSeH.. . . Selenium hexafluoride SeFe-Selenium tetrafluoride SeF, Selenyl fluoride SeOFj. 

Selenium hexafluoride (g) SeFs -51 Strontium iodide Srl2 -112... 

Sulphur, selenium and tellurium all form the hexafluoride by direct combination other hexahalides are unknown. SFg and SeFg are chemically inert, colourless gases. The former is non-toxic and at once the most inert sulphur compound and possibly the most inert non-ionic fluorine compound it resists fused KOH. The somewhat more reactive SeF is reduced by NHg above 200"". TeFg, also a colourless gas, is hydrolysed by water ... 

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