Order and disorder in difluorides The fluorite structureBeryllium fluoride glass
Difluorides are chemical compounds with two fluorine atoms per molecule (or per formula unit).
Metal difluorides are all ionic. Despite being highly ionic, the alkaline earth metal difluorides generally have extremely high lattice stability and are thus insoluble in water. The exception is beryllium difluoride. In addition, many transition metal difluorides are water-soluble.
Calcium difluoride is a notable compound. In the form of the mineral fluorite it is the major source of commercial fluorine. It also has an eponymic crystal structure, which is an end member of the spectrum starting from bixbyite and progressing through pyrochlore.
List of the difluorides
Examples of the difluorides include:
Alkaline earth metal difluorides The alkaline earth metals all exhibit the oxidation state +2, and form difluorides. The difluoride of radium is however not well established due to the element's high radioactivity. Beryllium difluoride Magnesium fluoride Calcium fluoride Strontium difluoride Barium fluoride Radium fluoride
{| class="wikitable sortable" |+ Solubility-related constants of alkaline earth metal fluorides ! Metal ! M2+ HE ! F− HE ! "MF2" unitHE ! MF2 latticeenergies (−kJ/mol) ! Solubility(mol/L) |- | Be | 2,455 | 458 | 3,371 | 3,526 | 25
| Mg | 1,922 | 458 | 2,838 | 2,978 | 0.0012 |- | Ca | 1,577 | 458 | 2,493 | 2,651 | 0.0002 |- | Sr | 1,415 | 458 | 2,331 | 2,513 | 0.0008 |- | Ba | 1,361 | 458 | 2,277 | 2,373 | 0.006
Lanthanide difluorides Neodymium difluoride Samarium difluoride Europium difluoride Dysprosium difluoride Thulium difluoride Ytterbium difluorideGeorg Brauer: Handbuch der Präparativen Anorganischen Chemie. 3., umgearb. Auflage. Band I. Enke, Stuttgart 1975, , p. 255.
Transition metal difluorides Compounds of the form MF2: Cadmium difluoride Chromium(II) fluoride Cobalt difluoride Copper(II) fluoride Iron(II) fluoride Manganese(II) fluoride Mercury difluoride Nickel difluoride Palladium difluoride Platinum difluoride Silver difluoride Vanadium difluoride Zinc difluoride
Post-transition metal difluorides Lead difluoride Tin(II) fluoride
Nonmetal and metalloid difluorides Dinitrogen difluoride Oxygen difluoride Dioxygen difluoride Selenoyl difluoride Sulfur difluoride Disulfur difluoride Thionyl difluoride Germanium difluoride
Noble gas difluorides Helium difluoride (hypothetical) Wu, R. Q. "HeF2 and ArF2 molecules from first-principles study" Argon difluoride (predicted) Krypton difluoride Xenon difluoride Radon difluoride
Bifluorides The bifluorides contain the two fluorine atoms in a covalent bonded to a hydrogen atom—the HF2− polyatomic ion—rather than as F− anions. Ammonium bifluoride Potassium bifluoride Sodium bifluoride
Organic difluorides
Ethanedioyl difluoride Ethylidene difluoride Carbonyl difluoride Carbon dibromide difluoride (dibromodifluoromethane) Carbon dichloride difluoride (dichlorodifluormethane) Methyl difluoride Methylphosphonyl difluoride Polyvinylidene difluoride
References
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