Borohydride
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A borohydride is a compound containing the tetrahydridoborate(III) ion, BH4−. Borohydride is a term also used for compounds containing BH3CN- (cyanotrihydroborate) and BH(C2H5)3- (triethylborohydride). Such compounds are mainly used as reducing agents in organic synthesis. The most important borohydride is sodium borohydride, but other salts are well known (see Table).[1]
[edit] Coordination complexes
Borohydrides are excellent ligands for metal ions. In most such compounds, the BH4- ligand is bidentate. The binary borohydrides containing only BH4- ligands are often fairly volatile. One example is uranium borohydride.
| Hydride CAS registry number | Mol.Wt. | Hydrogen Density | Density g/cm3 | m.p. (°C) | solubility in water (g/100 mL, 25 °C) | solubility in CH3OH (g/100 mL, 25 °C) | solubility in ether (g/100 mL, 25 °C) | solubility in THF (g/100 mL, 25 °C) |
|---|---|---|---|---|---|---|---|---|
| LiBH4
[16949-15-8] |
21.78 | 18.5 | 0.66 | 280 | 20.9 | decomp. (44 in EtOH) | 4.3 | 22.5 |
| NaBH4
[16940-66-2] |
37.83 | 10.6 | 1.07 | 505 | 55 | 16.4 (20 °C) | insol. | 0.1 (20 °C) |
| NaBH3CN
[25895-60-7] |
62.84 | 6.4 | 1.20 | 240 with deccomp. | deccomp. | 217 | insol. | 36 |
| KBH4
[13762-51-1] |
53.94 | 7.4 | 1.17 | 585 (under H2) | 19 | insol. | insol. | insol. |
| LiBH(C2H5)3
[22560-16-3] |
105.94 | 0.95 | unknown | unknown | decomp. | decomp. | na | high (supplied commercially) |
[edit] References
- ^ Peter Rittmeyer, Ulrich Wietelmann “Hydrides” in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_199
