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{{About|an inorganic cobalt complex cation|organic compounds with six hydroxyls|Alcohol (disambiguation){{!}}Alcohol}} |
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| verifiedrevid = 409452207 |
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| ImageFile = Hexol-2D-wedged.png |
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| ImageFile = Hexol-2D-wedged.png |
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| ImageSize = 250px |
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| ImageSize = 250px |
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| ImageFile1 = Hexol-cation-from-xtal-2000-3D-balls.png |
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| ImageFile1 = Hexol-cation-from-xtal-2000-3D-balls.png |
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| IUPACName = Triscobalt (III) ion |
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| CASNo_Ref = {{cascite|correct|??}} |
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| SMILES = O=S(=O)().0()()()12(0)(()()()()1)()()()()2.O=S(=O)().O=S(=O)() |
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| StdInChI=1S/4Co.12H3N.3H2O4S.6HO/c;;;;;;;;;;;;;;;;3*1-5(2,3)4;;;;;;/h;;;;12*1H3;3*(H2,1,2,3,4);6*1H/q-3;3*+1;;;;;;;;;;;;;;;;6*+1/p-6 |
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| Section2 = {{Chembox Properties |
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| StdInChIKey=WZHHSLNBXUIBMY-UHFFFAOYSA-H |
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| Co = 4 |
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| H = 42 |
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| N = 12 |
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| O = 18 |
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| Co=4 | H=42 | N=12 | O=18 | S=3 |
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| S = 3 |
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| Solubility = Sparingly soluble in water <ref name="InorgSyn" /> }} |
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In ], '''hexol''' is a ] with formula {<sub>3</sub>Co}<sup>6+</sup> — a ] consisting of four ] cations in ] +3, twelve ] molecules {{chem|NH|3}}, and six ] ]s {{chem|HO|-}}, with a net charge of +6. The hydroxy groups act as bridges between the central cobalt atom and the other three, which carry the ammonia ]s. |
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'''Hexol''' is a ] compound that was first prepared by ] in 1914 and represented the first non-carbon-containing ] compound. The salt with the ] of |
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(SO<sub>4</sub>)<sub>3</sub> was prepared starting from ]. |
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Salts of hexol, such as the sulfate {<sub>3</sub>Co}(SO<sub>4</sub>)<sub>3</sub>(H<sub>2</sub>O)<sub>x</sub>, are of historical significance as the first synthetic non-carbon-containing ] compounds.<ref>Miessler, G. L. and Tarr, D. A. (2003). ''Inorganic Chemistry'', 3rd ed., Pearson/Prentice Hall publisher, {{ISBN|0-13-035471-6}}.</ref> <ref>{{cite journal |doi=10.1002/chir.20912|title=Optical Activity and Alfred Werner's Coordination Chemistry|year=2011|last1=Ernst|first1=Karl-Heinz|last2=Berke|first2=Heinz|journal=Chirality|volume=23|issue=3|pages=187–189|pmid=20928897}}</ref> |
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] of this compound was possible by treating the hexol chloride salt with the ] silver <small>D</small>-(+)-bromo]sulphonate in dilute acetic acid. The <small>D</small>-hexol salt precipitated out from solution and the filtrate contained the <small>L</small>-hexol species. (<small>D</small>-hexol and <small>L</small>-hexol are ]s of each other; see ] for <small>D</small>/<small>L</small> notation.) |
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Werner also published a second achiral hexol (a minor byproduct from the production of ]) that he incorrectly identified as a linear trimer. |
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== Preparation== |
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Salts of hexol were first described by ],<ref>{{cite journal|author=Jørgensen, S. M. |title=Zur Konstitution der Kobalt-, Chrom- und Rhodiumbasen|journal= Zeitschrift für Anorganische Chemie |year=1898|volume =16| pages =184–197|doi=10.1002/zaac.18980160116|url=https://zenodo.org/record/1428082}}</ref> although it was Werner who recognized its structure.<ref name="hexol resolution"/> The cation is prepared by heating a solution containing the ''cis''-diaquotetramminecobalt(III) cation <sup>3+</sup> with a dilute base:<ref name="InorgSyn"/> |
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:4 <sup>3+</sup> + 2 HO<sup>−</sup> → {<sub>3</sub>Co}<sup>6+</sup> + 4 NH<sub>4</sub><sup>+</sup> + 4 H<sub>2</sub>O |
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In 2004 the second hexol was reinvestigated and found to be a ] species. |
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===Hexol sulfate=== |
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Starting with the sulfate and using ] as the base, depending on the conditions, one obtains the 9-hydrate, the 6-hydrate, or the 4-hydrate of hexol sulfate. These salts form dark brownish-violet or black tabular crystals, with low solubility in water. When treated with concentrated ], hexol sulfate converts to ''cis''-diaquotetramminecobalt(III) sulfate. In boiling dilute ], hexol sulfate further degrades with evolution of oxygen and nitrogen.<ref name="InorgSyn">{{cite book|author1=Kauffman, George B. |author2=Pinnell, Robert P. |title=Tris Cobalt(III) Sulfate 4-Hydrate|chapter=Tris[tetrammine-μ-dihydroxo-cobalt(III)]cobalt(III) Sulfate 4-Hydrate |series= Inorganic Syntheses|year= 1960 |volume =6|pages=176–179|doi=10.1002/9780470132371.ch56|isbn=9780470132371 }}</ref> |
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==Optical properties== |
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The hexol cation exists as two ]s that are mirror images of each other, depending on the arrangement of the bonds between the central cobalt atom and the three ] peripheral units . It belongs to the D{{sub|3}} ]. The nature of chirality can be compared to that of the ] anion {{chem||3-}}. |
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In a historic set of experiments, a salt of hexol with an optically active anion — specifically, its <small>D</small>-(+)-bromo]sulfonate – was ] into separate salts of the two cation isomers by ].<ref name="hexol resolution">{{cite journal | title=Über mehrkernige Metallammoniake | language=de |trans-title=Poly-nucleated Metal-amines | author=Werner, A. | journal=Ber. Dtsch. Chem. Ges. | year=1907 | volume=40 | issue=2 | pages=2103–2125 | doi=10.1002/cber.190704002126| url=https://zenodo.org/record/1426223 }}</ref> A more efficient resolution involves the ]. The hexol hexacation has a high ] of 2640°.<ref>{{cite book|author1=Yasui, Takaji |author2=Ama, Tomoharu |author3=Kauffman, George B. |title=Inorganic Syntheses |chapter=Resolution of the Dodecaamminehexa-μ-Hydroxo-Tetracobalt(III) Ion|year=1992|volume=29|pages=169–174|doi=10.1002/9780470132609.ch41|isbn=9780470132609 }}</ref> |
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=="Second hexol"== |
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Werner also described a second achiral hexol (a minor byproduct from the production of ]) that he incorrectly identified as a linear tetramer. The second hexol is hexanuclear (contains six cobalt centres in each ion), not tetranuclear.<ref>{{cite journal|title=The rediscovery of Alfred Werner's second hexol|journal=]|issue=20|year= 2004|pages=2322–2323|doi=10.1039/B408277J|last1=Jackson|first1=W. Gregory|last2=McKeon|first2=Josephine A.|last3=Zehnder|first3=Margareta|last4=Neuberger|first4=Markus|last5=Fallab|first5=Silvio|pmid=15490001}}</ref> Its point group is C{{sub|2h}}, and its formula is {{chem||6+}}, whereas that of hexol is {{chem||6+}}. |
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== References == |
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== References == |
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{{reflist}} |
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* A. Werner, H. Kuh, P. Wust Ber. '''1914''', 47, 196 |
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* ''The rediscovery of Alfred Werner's second hexol'' W. Gregory Jackson, Josephine A. McKeon, Margareta Zehnder, Markus Neuberger and Silvio Fallab ], '''2004''', (20), 2322 - 2323 |
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== External links == |
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== External links == |
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* Hexol Molecule of the Month September 1997 |
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* Hexol Molecule of the Month September 1997 |
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