In chemistry, germanate is a compound containing an oxyanion of germanium. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central germanium atom, [1] for example potassium hexafluorogermanate, K2GeF6. [2]
Germanium is similar to silicon forming many compounds with tetrahedral {GeO4} [2] units although it can also exhibit 5 [3] and 6 [2] coordination. Analogues of all the major types of silicates and aluminosilicates have been prepared. [4] For example, the compounds Mg2GeO4 (olivine and spinel forms), CaGeO3(perovskite structure), Be2GeO4 (phenakite structure) show the resemblance to the silicates. [4] BaGe4O9 has a complex structure containing 4 and 6 coordinate germanium.[ citation needed ] 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; [5] for example, MnGeO3 has a pyroxene type structure similar to that of MgSiO3 which is a significant mineral in the mantle. [6] [7] [8]
The alkali metal orthogermanates, M4GeO4, containing discrete GeO4−
4 ions, form acidic solutions containing GeO(OH)−
3, GeO
2(OH)2−
2 and [(Ge(OH)4)8(OH)3]3−. [2] Neutral solutions of germanium dioxide contain Ge(OH)4, but at high pH germanate ions such as GeO(OH)−
3, GeO
2(OH)2−
2 are present. [9]
Microporous germanate zeolites were first prepared in the 1990s. [10] [11] A common method of preparation is hydrothermal synthesis using an organic amine as a template (structure determining agent). [12] 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 {GeO4} tetrahedral unit compared to Si–O in {SiO4} and the narrower Ge–O–Ge angle (130°–140°) between corner shared tetrahedra allow for unusual framework structures. [13] A zeolite reported in 2005 [14] has large pores – 18.6 × 26.2 Å interconnected by channels defined by 30-membered rings (the naturally occurring zeolite faujasite with channels defined by 12-membered rings [15] ). Zeolites with frameworks containing silicon and germanium (silicogermanates), aluminium and germanium (aluminogermanates) and zirconium and germanium (zirconogermanates) are all known. [12] [16]
Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors silicon and tin. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature.
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.
A permanganate is a chemical compound with the manganate(VII) ion, MnO−
4, the conjugate base of permanganic acid. Because the manganese atom has a +7 oxidation state, the permanganate(VII) ion is a strong oxidising agent. The ion is a transition metal ion with a tetrahedral structure. Permanganate solutions are purple in colour and are stable in neutral or slightly alkaline media. The exact chemical reaction depends on the carbon-containing reactants present and the oxidant used. For example, trichloroethane (C2H3Cl3) is oxidised by permanganate ions to form carbon dioxide (CO2), manganese dioxide (MnO2), hydrogen ions (H+), and chloride ions (Cl−).
In inorganic nomenclature, a manganate is any negatively charged molecular entity with manganese as the central atom. However, the name is usually used to refer to the tetraoxidomanganate(2−) anion, MnO2−
4, also known as manganate(VI) because it contains manganese in the +6 oxidation state. Manganates are the only known manganese(VI) compounds.
In chemistry, an aluminate is a compound containing an oxyanion of aluminium, such as sodium aluminate. In the naming of inorganic compounds, it is a suffix that indicates a polyatomic anion with a central aluminium atom.
In chemistry tellurate is a compound containing an oxyanion of tellurium where tellurium has an oxidation number of +6. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central tellurium atom.
Bismuth germanium oxide or bismuth germanate is an inorganic chemical compound of bismuth, germanium and oxygen. Most commonly the term refers to the compound with chemical formula Bi4Ge3O12 (BGO), with the cubic evlitine crystal structure, used as a scintillator. (The term may also refer to a different compound with formula Bi12GeO20, an electro-optical material with sillenite structure, and Bi2Ge3O9.)
Aluminium phosphate is a chemical compound. In nature it occurs as the mineral berlinite. Many synthetic forms of aluminium phosphate are known. They have framework structures similar to zeolites and some are used as catalysts, ion-exchangers or molecular sieves. Commercial aluminium phosphate gel is available.
Selenium trioxide is the inorganic compound with the formula SeO3. It is white, hygroscopic solid. It is also an oxidizing agent and a Lewis acid. It is of academic interest as a precursor to Se(VI) compounds.
Germanium dioxide, also called germanium(IV) oxide, germania, and salt of germanium, is an inorganic compound with the chemical formula GeO2. It is the main commercial source of germanium. It also forms as a passivation layer on pure germanium in contact with atmospheric oxygen.
Osmium compounds are compounds containing the element osmium (Os). Osmium forms compounds with oxidation states ranging from −2 to +8. The most common oxidation states are +2, +3, +4, and +8. The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridium's +9 and is encountered only in xenon, ruthenium, hassium, iridium, and plutonium. The oxidation states −1 and −2 represented by the two reactive compounds Na
2[Os
4(CO)
13] and Na
2[Os(CO)
4] are used in the synthesis of osmium cluster compounds.
Germanium dichloride is a chemical compound of germanium and chlorine with the formula GeCl2. It is a yellow solid. Germanium dichloride is an example of a compound featuring germanium in the +2 oxidation state.
Germanium(II) hydroxide, normally written as Ge(OH)2, is a poorly characterised compound, sometimes called hydrous germanium(II) oxide or germanous hydroxide. It was first reported by Winkler in 1886.
Sodium germanate is an inorganic compound with the chemical formula Na2GeO3. It exists as a colorless solid. Sodium germanate is primarily used for the synthesis of other germanium compounds.
Lanthanum manganite is an inorganic compound with the formula LaMnO3, often abbreviated as LMO. Lanthanum manganite is formed in the perovskite structure, consisting of oxygen octahedra with a central Mn atom. The cubic perovskite structure is distorted into an orthorhombic structure by a strong Jahn–Teller distortion of the oxygen octahedra.
A selenite fluoride is a chemical compound or salt that contains fluoride and selenite anions. These are mixed anion compounds. Some have third anions, including nitrate, molybdate, oxalate, selenate, silicate and tellurate.
The borophosphates are mixed anion compounds containing borate and phosphate anions, which may be joined together by a common oxygen atom. Compounds that contain water or hydroxy groups can also be included in the class of compounds.
A selenate selenite is a chemical compound or salt that contains selenite and selenate anions (SeO32- and SeO42-). These are mixed anion compounds. Some have third anions.
Germanium compounds are chemical compounds formed by the element germanium (Ge). Germanium is insoluble in dilute acids and alkalis but dissolves slowly in hot concentrated sulfuric and nitric acids and reacts violently with molten alkalis to produce germanates ([GeO
3]2−
). Germanium occurs mostly in the oxidation state +4 although many +2 compounds are known. Other oxidation states are rare: +3 is found in compounds such as Ge2Cl6, and +3 and +1 are found on the surface of oxides, or negative oxidation states in germanides, such as −4 in Mg
2Ge. Germanium cluster anions (Zintl ions) such as Ge42−, Ge94−, Ge92−, [(Ge9)2]6− have been prepared by the extraction from alloys containing alkali metals and germanium in liquid ammonia in the presence of ethylenediamine or a cryptand. The oxidation states of the element in these ions are not integers—similar to the ozonides O3−.
Cobalt metagermanate is one of the germanates of cobalt, with chemical formula CoGeO3. It is paramagnetic at room temperature and turns antiferromagnetic at or below 32±1 K. It exists in two crystal forms, the orthorhombic and the monoclinic. It can be prepared by the reaction of cobalt(II,III) oxide (or cobalt(II) hydroxide) and germanium dioxide at high temperatures. The chemical vapor phase transfer method can also be used for its preparation.
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