7787-52-2

Usage

Uses

Used in Experimental Rockets and Fuel Cells:
Beryllium hydride (BeH2) is used as a source of hydrogen in experimental rockets and fuel cells. It liberates hydrogen gas when mixed with water, making it a valuable component for these applications.

Beryllium Compounds

In the mid-1960s, considerable interest in beryllium hydride was generated by its potential use with ammonium perchlorate oxidizer in solid propellants for rockets. Beryllium hydride, BeH2 , was prepared by action of ethereal lithium-aluminum hydride with beryllium chloride. A white powder resulted from which the complete removal of ether was difficult. The hydride is not stable above 125 °C (255 °F), decomposing into beryllium and hydrogen. Beryllium hydride is a three-dimensional polymer, considerably ionic in character and containing Be2+ and H- ions. Alternatively, it may be considered to be an electron-deficient molecule, similar to beryllium chloride and the beryllium alkyls, with hydrogen bridges between the two beryllium atoms (BeH2Be). Three-dimensional molecule of beryllium hydride

Preparation

Beryllium hydride is made by treating an ethereal solution of beryllium borohydride with triphenylphosphine, or by pyrolysis of di-tert-butylberyllium.

Safety Profile

Confirmed carcinogen. Adangerous fire hazard. When heated to 220°C it liberatesexplosive hydrogen gas. Reacts violently with methanol,water, and dilute acids. When heated to decomposition itemits toxic fumes of BeO. See BERYLLIUMCOMPOUNDS and HYDRIDE

InChI:InChI=1/Be.2H/q+2;2*-1

Upstream product

• 14390-89-7 beryllium 
• 74-90-8 hydrogen cyanide 
• 20722-83-2 [¹³C]hydrogen cyanide 
• 1333-74-0 hydrogen 

Relevant academic research and scientific papers

Infrared emission spectra of BeH2 and BeD2

Fourier transform spectrometer was used to record high resolution infrared spectra of beryllium dihydride (BeH2) and dideuteride. The BeH2 spectrum was recorded in the 1800-2900 cm-1 spectral region at an instrumental resolution of 0.03 cm-1 using a CaF2 beamsplitter. The equilibrium rotational constant of BeH2 was found to be 4.75366(2) cm-1.

Reactions of laser-ablated beryllium atoms with hydrogen cyanide in excess argon. FTIR spectra and quantum chemical calculations on BeCN, BeCN, HBeCN, and HBeNC

Laser-ablated beryllium atoms have been reacted with hydrogen cyanide (H12CN, H13CN, and D12CN) during condensation in excess argon at 6-7 K. In the matrix infrared spectrum, the major products observed are BeNC, BeCN, HBeNC, and HBeCN. Consistent with typical beryllium bonding, these new beryllium species are linear molecules. Density functional theory calculations on these products with the BP86 functional and 6-31 1G* basis sets predict vibrational frequencies extremely well, even for HBeCN where mixing between the nearly isoenergetic Be-H and C≡N stretching modes causes significant complications in the spectra. Although B3LYP and MP2 calculations are more sophisticated than the BP86 method, they do not predict the vibrational frequencies of these products nearly as well. More important is the carbon 12/13 isotopic frequency ratio as a description of the normal modes, and the BP86 method generates 12/13 ratios much closer to observed values for HBeCN than frequency ratios from the more time-consuming CISD method.

Reactions of beryllium atoms with hydrogen. Matrix infrared spectra of novel product molecules

Beryllium atoms formed by pulsed laser ablation have been codeposited with gaseous mixtures of hydrogen diluted in argon (concentrations varied from 25:1 to 100:1) onto a substrate at 10 K. Infrared spectroscopy on the reaction mixture identified six novel product molecules - BeH, BeH2, BeBeH, HBeBeH, HBeHBeH, and HBe(H)2-BeH. Assignments of infrared absorption bands were made on the basis of broad-band photolysis and annealing behavior, isotopic substitutions, and ab initio calculations performed at the MBPT(2) level. The major products initially are BeH (1970.0 cm-1) and the previously unobserved BeH2 molecule (v3 = 2159.1 cm-1, v2 = 697.9 cm-1) with formation of the three dimers HBeBeH, HBeHBeH, and HBe(H)2BeH at the expense of the initial reaction products upon annealing of the matrix to 30 K. The former dimer involves a stable Be-Be bond, and the latter dimers incorporate bridging hydrogen atoms. The new Be2H molecule (2013.7, 540.0 cm-1) is a minor product in these experiments, which exhibits a stronger Be-Be bond than Be2.