INNER-SHELL EXCITATION OF BORANES AND CARBORANES

Oscillator strengths for B 1s excitation of two borane cage compounds [nido-pentaborane(9) (B5H9) and nido-decaborane(14) (B10H14)] and for B 1s and C 1s excitation of three carborane cage compounds [closo-o-ca rborane (C2B10H12), nido-2,3-diethyl-2,3-dicarbahexaborane [(C2H5)2C2B 4H6], and 1,2-dicarbaundecaborane(11) (C2B9H11)] have been derived fro m inner-shell electron energy loss spectra (ISEELS), recorded under el ectric dipole scattering conditions. The spectral features have been a ssigned on the basis of spectral comparisons and of the results of sem iempirical (MNDO and extended Huckel) molecular orbital calculations. The 1,2-dicarbaundecaborane species was generated in situ by thermal d ecomposition of the bis(nido-1,2-dicarbaundecaborane)nickel species. T he preservation of the nido form of the ligand after decomposition is deduced from the experimental B 1s and C 1s spectra.