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In chemistry, germanate is a compound containing an oxyanion of
In chemistry, germanate is a compound containing an oxyanion of germanium
Germanium is a chemical element; it has Symbol (chemistry), symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid or a nonmetal in the carbon group that is chemically ...
. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central germanium atom, for example potassium hexafluorogermanate, K2GeF6.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier
Germanate oxy compounds
Germanium is similar to silicon forming many compounds with tetrahedral units although it can also exhibit 5 and 6 coordination. Analogues of all the major types of silicates and aluminosilicates have been prepared. For example, the compounds Mg2GeO4 (olivine
The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...
and spinel forms), CaGeO3( perovskite structure), Be2GeO4 ( phenakite structure) show the resemblance to the silicates. BaGe4O9 has a complex structure containing 4 and 6 coordinate germanium. Germanates are important for geoscience as they possess similar structures to silicates and can be used as analogues for studying the behaviour of silicate minerals found in the Earth's mantle; for example, MnGeO3 has a pyroxene type structure similar to that of MgSiO3 which is a significant mineral in the mantle.
Germanates in aqueous solutions
The alkali metal orthogermanates, M4GeO4, containing discrete ions, form acidic solutions containing , and Ge(OH)4)8(OH)3sup>3−. Neutral solutions of germanium dioxide contain Ge(OH)4, but at high pH germanate ions such as , are present.Germanate zeolites
Microporous germanate zeolites were first prepared in the 1990s. A common method of preparation is hydrothermal synthesis using an organic amine as a template (structure determining agent).Zeolites and Related Materials: Trends Targets and Challenges(SET), 1st Edition, 4th International FEZA Conference, 2008, Paris, France; Eds. Gedeon, Massiani, Babonneau; Elsevier Science; The frameworks are negatively charged due to extra oxide ions which leads to higher coordination numbers for germanium of 5 and 6. The negative charge is balanced by the positively charged amine molecules. In addition to the ability of germanium to exhibit 4, 5 or 6 coordination, the greater length of the Ge–O bond in the tetrahedral unit compared to Si–O in and the narrower Ge–O–Ge angle (130°–140°) between corner shared tetrahedra allow for unusual framework structures. A zeolite reported in 2005 has large pores – interconnected by channels defined by 30-membered rings (the naturally occurring zeolite faujasite with channels defined by 12-membered ringsHandbook Of Molecular Sieves: Structures, Rosemarie Szostak, 1992, Van Nostrand Reinhold, , ). Zeolites with frameworks containing silicon and germanium (silicogermanates), aluminium and germanium (aluminogermanates) and zirconium and germanium (zirconogermanates) are all known.See also
* Bismuth germanate (bismuth germanium oxide, BGO) * Sodium germanateReferences
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