Chemistry:Disodium enneaborate
| Identifiers | |
|---|---|
3D model (JSmol)
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|
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| Properties | |
| B9H22Na2O20 | |
| Molar mass | 485.43 g·mol−1 |
| Related compounds | |
Related compounds
|
Borax Sodium pentaborate Disodium octaborate Trisodium borate Sodium metaborate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Disodium enneaborate is the traditional name for a salt of sodium, boron, oxygen, and hydrogen, with elemental formula Na
2B
9H
22O
20 or Na
2B
9O
9 · 11H2O. It is the sodium borate with the highest boron/sodium ratio.[1]
Structure
The correct formula has since been determined to be (Na+
)
2[B
8O
11(OH)
4]2− · B(OH)
3 · 2H2O. The anion is a linear polymer with repeating unit [–B
8O
11(OH)
4–]2−. Sodium cations, water molecules, and undissociated boric acid molecules B(OH)
3 lie between the chains, held by numerous hydrogen bonds.[1]
The compound crystallizes in the monoclinic crystal system with space group P21/n. The cell parameters are a = 1021.3 pm, b = 1294.0 pm, c = 1245.7 pm, β = 93.070°, V = 1.6440 nm3, and Z = 2. The sodium cations occur in groups of four with interatomic distances of 378.30 pm and 379.32 pm.[1]
Reactions
Upon heating, disodium enneaborate initially becomes amorphous and then crystallizes as anhydrous disodium octaborate α-Na
2B
8O
13 along with amorphous B
2O
3. Notably, the former contains octaborate fundamental building blocks that are topologically equivalent to those in the enneaborate.[1]
References
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