AB-INITIO STUDY OF THE STRONG BINDING OF BEO TO LI, BE, AND B ATOMS IN THE HYPERSTOICHIOMETRIC LIOBE, BEOBE, AND BEOB MOLECULES

The equilibrium geometries and fundamental vibrational frequencies of LiOBe, BeOBe, and BeOB have been calculated using MP2(full)/6-311+G a nd QCISD/6-311+G levels of theory. The linear LiOBe ((2) Sigma(+)), B eOBe ((1) Sigma(+)), and BeOB ((2) Sigma(+)) structures were found to be the most stable, with representative dissociation energies of LiOBe , 114 kcal/mol (into LiO + Be) and 116 kcal/mol (into BeO + Li); BeOBe , 100 kcal/mol (into BeO + Be); and BeOB, 59 kcal/mol (into BO + Be) a nd 168 kcal/mol (into BeO + B). The strong binding of BeO to Li, Be, a nd B is related to the nature of the bonding in BeO, in which the char ge on O is significantly below -2. The bonding in BeO was further exam ined by comparing to the single Be-O bonds in BeOH and HBeOH. The bond in BeO was found to be only 0.06 Angstrom shorter than the Be-O singl e bonds in HBeOH and BeOH and to have about the same dissociation ener gy as these single bonds, in agreement with our statement that BeO doe s not possess a conventional double bond.