Structure, Preparation, and General Properties
MgCl2 crystallizes in the cadmium chloride motif, which features octahedral Mg. A variety of hydrates are known with the formula MgCl2(H2O)x, and each loses water with increasing temperature: x = 12 (-16.4 °C), 8 (-3.4 °C), 6 (116.7 °C), 4 (181 °C), 2 (ca. 300 °C). In the hexahydrate, the Mg2+ remains octahedral, but is coordinated to six water ligands. The thermal dehydration of the hydrates MgCl2(H2O)x (x = 6, 12) does not occur straightforwardly.
As suggested by the existence of some hydrates, anhydrous MgCl2 is a Lewis acid, although a very weak one.
In the Dow process, magnesium chloride is regenerated from magnesium hydroxide using hydrochloric acid:
- Mg(OH)2(s) + 2 HCl → MgCl2(aq) + 2 H2O(l)
It can also be prepared from magnesium carbonate by a similar reaction.
In most of its derivatives, MgCl2 forms octahedral complexes. Derivatives with tetrahedral Mg2+ are less common. Examples include salts of (tetraethylammonium)2MgCl4 and adducts such as MgCl(TMEDA).
Read more about this topic: Magnesium Chloride
Famous quotes containing the words general and/or properties:
“In effect, to follow, not to force the public inclination; to give a direction, a form, a technical dress, and a specific sanction, to the general sense of the community, is the true end of legislature.”
—Edmund Burke (1729–1797)
“A drop of water has the properties of the sea, but cannot exhibit a storm. There is beauty of a concert, as well as of a flute; strength of a host, as well as of a hero.”
—Ralph Waldo Emerson (1803–1882)