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| Order and disorder in difluorides |
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| The fluorite structure | Beryllium fluoride glass |
Difluorides are chemical compounds with two fluorine atoms per molecule (or per formula unit).
Metal difluorides are all ionic compound. Despite being highly ionic, the alkaline earth metal difluorides generally have extremely high lattice stability and are thus solubility 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.
>+ Solubility-related constants of alkaline earth metal fluorides
! Metal
! M2+ hydration energy
! F− HE
! "MF2" unit
HE
! MF2 lattice
energies (−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 difluoride
[Georg 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
Nonmetal and metalloid difluorides
-
Dinitrogen difluoride
-
Oxygen difluoride
-
Dioxygen difluoride
-
Selenoyl difluoride
-
Sulfur difluoride
-
Disulfur difluoride
-
Thionyl difluoride
-
Germanium difluoride
Noble gas difluorides
Bifluorides
The contain the two fluorine atoms in a covalent bond 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
Bibliography
