Difluoride
{{confuse|Bifluoride}}
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| colspan="2" style="text-align:center;"| Order and disorder in difluorides |
| style="width:155px; padding-right:5px;" | File:Fluorite unit cell (ionic) - cropped.png
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| style="width:155px; padding-right:5px; "|The fluorite structure | style="width:155px; padding-left:5px; "|Beryllium 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{{sfn|Wiberg|Wiberg|Holleman|2001|pp=XXXVI–XXXVII}} ! F− HE{{sfn|Wiberg|Wiberg|Holleman|2001|p=XXXVI}} ! "MF2" unit ! MF2 lattice ! Solubility |
| 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{{cn|date=May 2024}}
- Samarium difluoride{{cite book|last1=Müller |first1=Bernd G. |chapter=Lanthanide Fluorides |title=Synthesis of Lanthanide and Actinide Compounds |date=1991 |volume=2 |pages=55–65 |doi=10.1007/978-94-011-3758-4_2}}
- Europium difluoride
- Dysprosium difluoride{{cn|date=May 2024}}
- Thulium difluoride
- Ytterbium difluorideGeorg Brauer: Handbuch der Präparativen Anorganischen Chemie. 3., umgearb. Auflage. Band I. Enke, Stuttgart 1975, {{ISBN|3-432-02328-6}}, p. 255.
= Transition metal difluorides=
= Post-transition metal difluorides =
=Nonmetal and metalloid difluorides=
= Noble gas difluorides =
=Bifluorides=
The bifluorides contain the two fluorine atoms in a covalently bound HF2− polyatomic ion rather than as F− anions.
=Organic difluorides=
- Ethanedioyl difluoride
- Ethylidene difluoride
- Carbonyl difluoride
- Carbon dibromide difluoride (dibromodifluoromethane)
- Carbon dichloride difluoride (dichlorodifluormethane)
- Methyl difluoride
- Methylphosphonyl difluoride
- Polyvinylidene difluoride
References
{{reflist}}
Bibliography
- {{cite book |last1=Greenwood |first1=N. N. |last2=Earnshaw |first2=A. |title=Chemistry of the Elements |publisher=Butterworth Heinemann |year=1998 |isbn=0-7506-3365-4 |edition=second }}
- {{cite book |last=Lide |first=David R. |title=Handbook of chemistry and physics|url=https://archive.org/details/crchandbookofche81lide |url-access=registration |publisher=CRC Press|year=2004|edition=84th|isbn=0-8493-0566-7 }}
- {{cite book|last1=Wiberg |first1= Egon |last2= Wiberg |first2=Nils |last3=Holleman |first3=Arnold Frederick|title=Inorganic chemistry|url=https://books.google.com/books?id=Mtth5g59dEIC|access-date=3 March 2011|year=2001|publisher=Academic Press|isbn=978-0-12-352651-9}}
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