Tellurate

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The structure of metatellurate and orthotellurate Tellurate.png
The structure of metatellurate and orthotellurate

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. [1]

Contents

Tellurium oxyanions

Historically the name tellurate was only applied to oxyanions of tellurium with oxidation number +6, formally derived from telluric acid Te(OH)6, and the name tellurite referred to oxyanions of tellurium with oxidation number +4, formally derived from tellurous acid (HO)2TeO and these names are in common use. However tellurate and tellurite are often referred to as tellurate(VI) and tellurate(IV) respectively in line with IUPAC renaming recommendations. [1] The metatellurate ion is TeO2−
4 and the orthotellurate ion is TeO6−
6. Other oxyanions include pentaoxotellurate, TeO4−
5, [2] ditellurate, Te
2O8−
10 [3] and polymeric anions with 6-coordinate tellurium such as (TeO4−
5)n. [4]

Metatellurates

The metatellurate ion TeO2−
4 is analogous to the sulfate ion, SO2−
4 and the selenate ion, SeO2−
4. Whereas many sulfates and selenates form isomorphous salts [5] the tetrahedral metatellurate ion is only found in a few compounds such as the tetraethylammonium salt (NEt 4)2TeO4. [6] Many compounds with a stoichiometry that suggests the presence of a metatellurate ion actually contain polymeric anions containing 6-coordinate tellurium(VI), for example sodium tellurate, Na2TeO4 which contains octahedral tellurium centers sharing edges. [7]

TeO2−
4 → TeO2−
3 + 1⁄2 O2      (E0 = −1.042 V)

The E0 or standard reduction potential value is significant as it gives an indication of the strength of the tellurate ion as an oxidizing agent. [8]

Orthotellurates

Compounds containing the octahedral TeO6−
6 anion are known, these include Ag6TeO6, Na6TeO6 and Hg3TeO6. [9] There are also hydroxyoxotellurates, containing protonated TeO6−
6, such as (NH4)2TeO2(OH)4 (sometimes written as NH4TeO4·2H2O) which contains the octahedral TeO
2(OH)2−
4 ion. [10]

TeO4−
5 ion

The compound Cs2K2TeO5 contains TeO4−
5 ions which are trigonal bipyramidal. [2] The compound Rb6Te2O9 contains both TeO4−
5 and TeO2−
4 anions. [11] Other compounds whose stoichiometry suggests the presence of TeO4−
5 may contain either the dimeric Te
2O8−
10 made up of two edge-sharing {TeO6} as in Li4TeO5 [3] and Ag4TeO5 [12] or corner-sharing {TeO6} octahedra as in Hg2TeO5. [4]

Polymeric tellurate ions

The dimeric Te
2O8−
10 made up of two edge sharing {TeO6} octahedra is found in the compound Li4TeO5. [3] A similar hydroxy-oxy anion, Te2O6(OH)4 is found in sodium potassium ditellurate(VI) hexahydrate, Na0.5K3.5Te2O6(OH)4·6H2O which contains pairs of edge sharing octahedra. [13] Polymeric chain anions consisting of corner-shared {TeO6} octahedra (TeO5)4n−
n are found, for example in Li4TeO5. [3]

Aqueous chemistry

In aqueous solution tellurate ions are 6 coordinate. In neutral conditions the pentahydrogen orthotellurate ion, H
5TeO−
6, is the most common; in basic conditions, the tetrahydrogen orthotellurate ion, H
4TeO2−
6, and in acid conditions, orthotelluric acid, Te(OH)6 or H6TeO6 is formed. [8]

Structural comparisons with oxyanions of sulfur and selenium

Sulfur(VI) oxyanions have a coordination number of 4 and in addition to the tetrahedral sulfate ion, SO2−
4, the pyrosulfate, S
2O2−
7, trisulfate, S
3O2−
10 and pentasulfate S
5O2−
16 ions all contain 4-coordinate sulfur and are built from corner-shared {SO4} tetrahedra. [14] Selenate compounds include many examples of four coordinate selenium, principally the tetrahedral SeO2−
4 ion and the pyroselenate ion, Se
2O2−
7 which has a similar structure to the pyrosulfate ion. [15] Unlike sulfur there are examples of a 5-coordinate selenium oxyanion, SeO4−
5 and one example of SeO6−
6. [16] [17] [18]

NMR spectroscopy

Tellurium has two NMR active nuclei, 123Te and 125Te. 123Te has an abundance of 0.9% and a nuclear spin (I) of ⁠1/2⁠. 125Te has an abundance of 7% and an equivalent nuclear spin. [19] 125Te is more commonly performed because it has a higher sensitivity. [20] The metatellurate anion has a chemical shift around 610 ppm when analyzed using 125Te NMR at 25 °C at a frequency of 94.735  MHz and referenced externally against aqueous 1.0  M telluric acid. [6]

The tellurate suffix in the naming of inorganic compounds

Following the IUPAC Red Book(2005) [1] some examples are:

Related Research Articles

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y. Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound H
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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.

<span class="mw-page-title-main">Telluric acid</span> Chemical compound (Te(OH)6)

Telluric acid, or more accurately orthotelluric acid, is a chemical compound with the formula Te(OH)6, often written as H6TeO6. It is a white crystalline solid made up of octahedral Te(OH)6 molecules which persist in aqueous solution. In the solid state, there are two forms, rhombohedral and monoclinic, and both contain octahedral Te(OH)6 molecules, containing one hexavalent tellurium (Te) atom in the +6 oxidation state, attached to six hydroxyl (–OH) groups, thus, it can be called tellurium(VI) hydroxide. Telluric acid is a weak acid which is dibasic, forming tellurate salts with strong bases and hydrogen tellurate salts with weaker bases or upon hydrolysis of tellurates in water. It is used as tellurium-source in the synthesis of oxidation catalysts.

<span class="mw-page-title-main">Tellurite</span> Ion

The tellurite ion is TeO2−
3. A tellurite (compound), for example sodium tellurite, is a compound that contains this ion. They are typically colorless or white salts, which in some ways are comparable to sulfite. A mineral with the formula TeO2 is called tellurite.

<span class="mw-page-title-main">Teflic acid</span> Chemical compound

Teflic acid is a chemical compound with the formula HOTeF5. This strong acid is related to orthotelluric acid, Te(OH)6. Teflic acid has a slightly distorted octahedral molecular geometry.

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.

<span class="mw-page-title-main">Chromium compounds</span> Chemical compounds containing chromium

Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist.

Thiophosphates (or phosphorothioates, PS) are chemical compounds and anions with the general chemical formula PS
4−xO3−
x (x = 0, 1, 2, or 3) and related derivatives where organic groups are attached to one or more O or S. Thiophosphates feature tetrahedral phosphorus(V) centers.

<span class="mw-page-title-main">Osmium(IV) chloride</span> Chemical compound

Osmium(IV) chloride or osmium tetrachloride is the inorganic compound composed of osmium and chlorine with the empirical formula OsCl4. It exists in two polymorphs (crystalline forms). The compound is used to prepare other osmium complexes.

<span class="mw-page-title-main">Molybdate</span> Chemical compound of the form –O–MoO₂–O–

In chemistry, a molybdate is a compound containing an oxyanion with molybdenum in its highest oxidation state of +6: O−−Mo(=O)2−O−. Molybdenum can form a very large range of such oxyanions, which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state. The larger oxyanions are members of group of compounds termed polyoxometalates, and because they contain only one type of metal atom are often called isopolymetalates. The discrete molybdenum oxyanions range in size from the simplest MoO2−
4, found in potassium molybdate up to extremely large structures found in isopoly-molybdenum blues that contain for example 154 Mo atoms. The behaviour of molybdenum is different from the other elements in group 6. Chromium only forms the chromates, CrO2−
4, Cr
2O2−
7, Cr
3O2−
10 and Cr
4O2−
13 ions which are all based on tetrahedral chromium. Tungsten is similar to molybdenum and forms many tungstates containing 6 coordinate tungsten.

Tellurium compounds are compounds containing the element tellurium (Te). Tellurium belongs to the chalcogen family of elements on the periodic table, which also includes oxygen, sulfur, selenium and polonium: Tellurium and selenium compounds are similar. Tellurium exhibits the oxidation states −2, +2, +4 and +6, with +4 being most common.

The telluride bromides are chemical compounds that contain both telluride ions (Te2−) and bromide ions (Br−). They are in the class of mixed anion compounds or chalcogenide halides.

The telluride phosphides are a class of mixed anion compounds containing both telluride and phosphide ions. The phosphidotelluride or telluridophosphide compounds have a [TeP]3− group in which the tellurium atom has a bond to the phosphorus atom. A formal charge of −2 is on the phosphorus and −1 on the tellurium. There is no binary compound of tellurium and phosphorus. Not many telluride phosphides are known, but they have been discovered for noble metals, actinides, and group 4 elements.

The telluride iodides are chemical compounds that contain both telluride ions (Te2−) and iodide ions (I−). They are in the class of mixed anion compounds or chalcogenide halides.

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 borotellurates are heteropoly anion compounds which have tellurate groups attached to boron atoms. The ratio of tellurate to borate reflects the degree of condensation. In [TeO4(BO3)2]8- the anions are linked into a chain. In [TeO2(BO3)4]10− the structure is zero dimensional with isolated anions. These arrangements of oxygen around boron and tellurium can have forms resembling silicates. The first borotellurates to be discovered were the mixed sodium rare earth compounds in 2015.

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.

A tellurite tellurate is chemical compound or salt that contains tellurite and tellurate anions [TeO3]2- [TeO4 ]2-. These are mixed anion compounds, meaning the compounds are cations that contain one or more anions. Some have third anions. Environmentally, tellurite [TeO3]2- is the more abundant anion due to tellurate's [TeO4 ]2- low solubility limiting its concentration in biospheric waters. Another way to refer to the anions is tellurium's oxyanions, which happen to be relatively stable.

Carbide iodides are mixed anion compounds containing iodide and carbide anions. Many carbide iodides are cluster compounds, containing one, two or more carbon atoms in a core, surrounded by a layer of metal atoms, and encased in a shell of iodide ions. These ions may be shared between clusters to form chains, double chains or layers.

References

  1. 1 2 3 Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 – Full text (PDF)
  2. 1 2 Untenecker, H.; Hoppe, R. (1986). "Die koordinationszahl 5 bei telluraten: Cs2K2[TeO5]". Journal of the Less Common Metals. 124 (1–2): 29–40. doi:10.1016/0022-5088(86)90474-1. ISSN   0022-5088.
  3. 1 2 3 4 Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN   0-19-855370-6
  4. 1 2 Weil, Matthias (2003). "Preparation, Thermal Behaviour and Crystal Structure of the Basic Mercury(II) Tetraoxotellurate(VI), Hg2TeO5, and Redetermination of the Crystal Structure of Mercury(II) Orthotellurate(VI), Hg3TeO6". Zeitschrift für anorganische und allgemeine Chemie. 629 (4): 653–657. doi:10.1002/zaac.200390111. ISSN   0044-2313.
  5. ↑ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, p. 531, ISBN   0-471-19957-5
  6. 1 2 Konaka, Saki; Ozawa, Yoshiki; Yagasaki, Atsushi (2008). "Tetrahedral Tellurate". Inorganic Chemistry. 47 (4): 1244–1245. doi:10.1021/ic701578p. ISSN   0020-1669. PMID   18220344.
  7. ↑ Kratochvíl, B.; Jenšovský, L. (1977). "The crystal structure of sodium metatellurate". Acta Crystallographica Section B. 33 (8): 2596–2598. doi:10.1107/S0567740877008978. ISSN   0567-7408.
  8. 1 2 Frost, Ray L. (2009). "Tlapallite H6(Ca,Pb)2(Cu,Zn)3SO4(TeO3)4TeO6, a multi-anion mineral: A Raman spectroscopic study" (PDF). Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 72 (4): 903–906. Bibcode:2009AcSpA..72..903F. doi:10.1016/j.saa.2008.12.008. ISSN   1386-1425. PMID   19167264.
  9. ↑ Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, p. 593, ISBN   0-12-352651-5
  10. ↑ Johansson, G. B.; Lindqvist, O.; Moret, J. (1979). "Diammonium tellurium(VI) dioxide tetrahydroxide" (PDF). Acta Crystallographica Section B. 35 (7): 1684–1686. doi:10.1107/S056774087900741X. ISSN   0567-7408.
  11. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 782. ISBN   978-0-08-037941-8.
  12. ↑ Weil, Matthias (2007). "New Silver Tellurates – The Crystal Structures of a Third Modification of Ag2Te2O6 and of Ag4TeO5". Zeitschrift für anorganische und allgemeine Chemie. 633 (8): 1217–1222. doi:10.1002/zaac.200700106. ISSN   0044-2313.
  13. ↑ Kratochvíl, B.; Podlahová, J.; Jenšovský, L. (1978). "Sodium potassium ditellurate(VI) hexahydrate". Acta Crystallographica Section B. 34 (1): 256–258. doi:10.1107/S056774087800271X. ISSN   0567-7408.
  14. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 712. ISBN   978-0-08-037941-8.
  15. ↑ Paetzold, R.; Amoulong, H.; Růžička, A. (1965). "Untersuchungen an Selen-Sauerstoff-Verbindungen. XXVI. Schwingungsspektrum und Kraftkonstanten des Diselenations". Zeitschrift für anorganische und allgemeine Chemie. 336 (5–6): 278–285. doi:10.1002/zaac.19653360508. ISSN   0044-2313.
  16. ↑ Haas, Helmut; Jansen, Martin (2000). "Octahedral SeO66− and Square-Pyramidal SeO54−, Two New Oxoselenate Anions". Angewandte Chemie. 39 (23): 4362–4364. doi:10.1002/1521-3773(20001201)39:23<4362::AID-ANIE4362>3.0.CO;2-S. ISSN   1433-7851.
  17. ↑ Orosel, Denis; Dinnebier, Robert; Jansen, Martin (2006). "High-Pressure Synthesis and Structure Determination of K6(SeO4)(SeO5), the First Potassium Orthoselenate(VI)". Inorganic Chemistry. 45 (26): 10947–10950. doi:10.1021/ic061548v. ISSN   0020-1669. PMID   17173453.
  18. ↑ Haas, H.; Jansen, M. (2001). "Na4SeO5, ein neues Pentaoxoselenat(VI) – Synthese, Charakterisierung und Vergleich mit isotypem Na4MoO5". Zeitschrift für anorganische und allgemeine Chemie. 627 (4): 755–760. doi:10.1002/1521-3749(200104)627:4<755::AID-ZAAC755>3.0.CO;2-L. ISSN   0044-2313.
  19. ↑ Housecroft, C. E.; Sharpe, A. G. (2008). Inorganic Chemistry (3rd ed.). Prentice Hall. ISBN   978-0-13-175553-6.
  20. ↑ Drago, R. S. Physical Methods for Chemists 2nd ed.; Surfside Scientific Publishers: Gainesville, FL 1992.
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