Hexol

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| ImageFile = Hexol 2D wedged. png
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| ImageFile1 = Hexol cation from xtal 2000 3D balls. png
| IUPACName = Tris[tetrammine μ dihydroxocobalt(III)]cobalt (III) ion
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|Section2=Chembox Properties
| Co=4 | H=42 | N=12 | O=18 | S=3
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| Solubility = Sparingly soluble in water

Salts of hexol were first described by Jørgensen, although it was Werner who recognized its structure.

The hexol cation exists as two optical isomers that are mirror images of each other, depending on the arrangement of the bonds between the central cobalt atom and the three bidentate peripheral units [Co(NH3)4(HO)2]. It belongs to the D point group. The nature of chirality can be compared to that of the ferrioxalate anion
In a historic set of experiments, a salt of hexol with an optically active anion — specifically, its D (+) bromocamphorsulfonate – was resolved into separate salts of the two cation isomers by fractional crystallisation. A more efficient resolution involves the bis(tartrato)diantimonate(III) anion. The hexol hexacation has a high specific rotation of 2640°.

Werner also described a second achiral hexol (a minor byproduct from the production of Fremy's salt) that he incorrectly identified as a linear tetramer. The second hexol is hexanuclear (contains six cobalt centres in each ion), not tetranuclear. Its point group is C, and its formula is , whereas that of hexol is .