Beryllium borohydride

Beryllium borohydride is an inorganic compound with the chemical formula Be(BH₄)₂.

Beryllium borohydride

Names
IUPAC name Beryllium borohydride
Other names Beryllium tetrahydroborate(1-)
Identifiers
CAS Number	17440-85-6
3D model (JSmol)	Interactive image
PubChem CID	6101896
InChI InChI=1S/2BH4.Be/h2*1H4;/q2*-1;+2 Key: ONQXRAXVSQRPSX-UHFFFAOYSA-N
SMILES [Be+2].[BH4-].[BH4-]
Properties
Chemical formula	Be(BH4)2
Molar mass	38.70 g/mol
Appearance	white crystals
Density	0.604 g/cm^3
Melting point	91.3 °C (196.3 °F; 364.4 K)
Boiling point	123 °C (253 °F; 396 K) decomposes
Solubility in water	reacts
Solubility	soluble in benzene, diethyl ether
Structure
Crystal structure	tetragonal
Space group	I41cd, No. 110
Thermochemistry
Std enthalpy of formation (ΔfH^⦵298)	-108 kJ/mol
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.002 mg/m^3 C 0.005 mg/m^3 (30 minutes), with a maximum peak of 0.025 mg/m^3 (as Be)[1]
REL (Recommended)	Ca C 0.0005 mg/m^3 (as Be)[1]
IDLH (Immediate danger)	Ca [4 mg/m^3 (as Be)][1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Structure

The crystal structure is made up of a helical polymer of BH₄Be and BH₄ structure units.[2]

Production

Beryllium borohydride is formed by the reaction of beryllium hydride with diborane in an ether solution.

Application

The purest beryllium hydride is obtained by the reaction of triphenylphosphine, PPh₃, with beryllium borohydride, Be(BH₄)₂:[3]

Be(BH₄)₂ + 2 PPh₃ → 2 Ph₃PBH₃ + BeH₂

References

1. NIOSH Pocket Guide to Chemical Hazards. "#0054". National Institute for Occupational Safety and Health (NIOSH).
2. Marynick, Dennis S.; Lipscomb, William N. (1 April 1972). "Crystal structure of beryllium borohydride". Inorganic Chemistry. 11 (4): 820–823. doi:10.1021/ic50110a033.
3. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.