Selenium tetrachloride hexafluoride

SELENIUM TETRACHLORIDE SELENIUM HEXAFLUORIDE SELENIUM OXYCHLORIDE SELENIUM DIOXIDE SILICON... 

Phosphorus pentafluoride Polarine oil Selenium mustard Silicon tetrafluoride Strontium chlorate Strontium permanganate Sulfur chloropentafluoride Sulfur dichloride Sulfur hexafluoride Sulfur monochloride Titanium tetrachloride Thiocarhonyl dichloride Thionyl fluoride Thioptiosgene Triethyl aluminum Trifluoromethyl iodide Triisohutylaluminum Trimethylaluminum Vanadium tetrachloride Vincennite Vinyl bromide Vinylmagnesium bromide Xenon difluoride Zinc arsenide... 

The heavier elements of the group, S, Se and Te all form tetralluorides, EF4 and hexafluorides, EF6- If the central atom in these compounds form Lewis electron pair bonds to all the ligating fluorine atoms, it must accommodate five or six electron pairs in the valence shell, and we refer to the atoms as hypervalent. Sulfur forms no further homoleptic hypervalent derivatives. Selenium forms a solid tetrachloride, but as mentioned in the last paragraph, it decomposes on evaporation. Tellurium forms a solid tetrachloride, which may be evaporated without decomposition, as well as tetraphenyl-, tetramethyl- and hexamethyl- derivatives. 

---