Infrared and Raman Spectra of Solid Beryllium Borohydride, BeB2H8

Infrared and Raman spectra of solid BeB2H8, BeB2D8, Be10B2D8, and BeB2D7H have been obtained at 20 and 180°K. These data indicate that a structural change occurs in going from the vapor to the solid and suggest the presence of the borohydride anion, BH4−, paired with an unusual hydrogen bridged cation, +BeBH4. A detailed examination of the isotopic frequency shifts supports this view and an excellent fit of the BH4− frequencies is obtained from a normal coordinate analysis. Reasonable assignments of the +BeBH4 fundamentals are given and the structure of the +BeBH4 ion is discussed.