BeH2, Beryllium Hydride

As usual, the principal symmetry axis is taken to be aligned with Z, and so the Be 2s and 2pj AOs belong to the CTg+ and cTu representations respectively, while 2p j and 2py are 

The next orbital is 3 Tu, which contains the Be 2p and SALC of H(ls) orbitals. This is the HOMO, as there are only four electrons to accommodate in BeH2. The LUMOs are the degenerate pair of Be 7i orbitals there are no corresponding H orbitals low enough in energy to form a significant interaction, and so these are nonbonding states. 

The linear structure of BeH2 maximizes the overlap between the Be 2pj and the com- 

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Any atom surrounded by only two groups is linear and has a bond angle of 180°. Two examples illustrating this geometry are BeH2 (beryllium hydride) and HC=CH (acetylene). We consider each carbon atom in acetylene separately. Because each C is surrounded by two atoms and no lone pairs, each H-C-C bond angle in acetylene is 180°, and therefore all four atoms are linear. 

BeH2 beryllium hydride 7787-52-2 25.00 0.6500 1 742 CaH609P2 calcium dihydrogen phosphate monohydrate 10031-30-8 25.00 2.2200 1... 

LiH (lithium hydride) ionic compound BeH2 (beryllium hydride) covalent compound B2H6 (diborane, you aren t expected to know that name) molecular compound CH4 (methane, do you know that one ) molecular compound NH3 (ammonia, you should know that one) molecular compound H2O (water, if you didn t know that one, you should be ashamed) molecular compound HF (hydrogen fluoride) molecular compound. LiH and BeH2 are solids, B2H6, CH4, NH3, and HF are gases, and H2O is a liquid. 

Beryllium Hydride. BeryUium hydride [13597-97-2] is an amorphous, colorless, highly toxic polymeric soHd (H = 18.3%) that is stable to water but hydroly2ed by acid (8). It is insoluble in organic solvents but reacts with tertiary amines at 160°C to form stable adducts, eg, (R3N-BeH2 )2 (9). It is prepared by continuous thermal decomposition of a di-/-butylberylhum-ethyl ether complex in a boiling hydrocarbon (10). 

Problem 8-6. What is the Schrodinger equation for Beryllium Hydride, BeH2 ... 

Theoretically, both aluminum hydride, AIH3, and beryllium hydride, BeH2, are attractive fuels because of their high heat release and gas volume contribution. Both axe difficult to manufacture and both deteriorate chemically during storage, due to loss of hydrogen. Because of these difficulties, coupled with relatively modest Isp gains, these compounds remain experimental. 

Apart from the vast number of compounds containing B-H-B bridge bonds, a good many other three-centre E-H-E links are found, especially where E or E is B, Be or Li. Beryllium hydride BeH2, is a onedimensional polymeric solid (isostructural with BeCl2 and SiS2 see Section 3.3), whose structure can be rationalised in terms of Be-H-Be (3c, 2e) bridge bonds ... 

Examples of compounds that have fewer than eight valence electrons are beryllium hydride, BeH2 and boron trifluoride, BF3. 

IV. E.l. The metallic hydrides, such as pentaborane (B5H9), lithium hydride (LiH), and beryllium hydride (BeH2) are attractive candidates if the temperature and pressure of operation fall into a range where evaporation of the metal will occur (48). Such propellants would have a definite advantage over hydrogen in their storability and relatively high densities. 

Draw the Lewis structure for beryllium hydride, BeH2. Draw the orbitals that overlap in the bonding of BeH2, and label the hybridization of each orbital. Predict the H—Be — H bond angle. 

Consider how we might explain the bonding in a compound of divalent beryllium, such as beryllium hydride, BeH2. The beryllium atom, with only four electrons, has a configuration of ls22s. 

The main dijfference between a linear H3 system and beryllium hydride, BeH2, which is a linear molecule, is that the central atom now contributes two valence electrons and four atomic orbitals the 2s orbital, which is doubly occupied in an isolated ground state Be atom (configuration Is, 2s ), and the three 2p orbitals which are empty in Be but lie not too far above 2s in energy. Graphically, we have ... 

Beryllium hydride, BeH2, has four valence electrons, two from beryllium and one each from the two hydrogen atoms, all of which appear in its Lewis diagram. In VSEPR theory, the steric number is 2, so the molecule is predicted to be linear, and this prediction is verified by experiment. The electron configuration of the central atom is Be (ls) (2s). There are no unpaired electrons to overlap with H(ls) orbitals, so the VB model fails to predict the formation of BeHi. 

Beryllium hydride combines with complexes MA1R H4 (M = Li, Na, R = hydrocarbyl, n = 1-4) to form species BeH2-MAlR H4 . 

Several compounds of beryllium have important applications. The most commercially important beryllium compound is beryllium oxide (BeO), which is used in high-temperature applications, such as crucibles, microwave ovens, ceramics, and insulators. Beryllium oxide also finds use in gyroscopes and military vehicle armor. Beryllium chloride (BeCl2) is used as a catalyst in the synthesis of organic chemicals. Beryllium hydride (BeH2) is a source of hydrogen gas when mixed with water. Beryllium carbide (Be2C) is a source of neutrons in nuclear reactors. 

In some compounds the number of electrons surrounding the central atom in a stable molecule is fewer than eight. Consider, for example, beryllium, which is a Group 2A (and a second-period) element. The electron configuration of beryllium is ls 2s it has two valence electrons in the 2s orbital. In the gas phase, beryllium hydride (BeH2) exists as discrete molecules. The Lewis structure of BeH2 is... 

The bonds in beryllium hydride (BeH2) molecules are polar, and yet the dipole moment of the molecule is zero. Explain. 

Draw the Lewis structure of beryllium hydride, BeH2. 

Beryllium Hydride. BeH2 mol wt 11.03. Be 81.69%, H 18.31%. Lower purity material prepd by treating dimethylberyllium with LiAlH4 in ether Barbaras et al. J. Am. Chem. Soc. 73, 4585 (1951) higher purity by pyrolysis... 

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