SYNTHESIS OF ICOSAHEDRAL CARBORANES FOR 2ND-HARMONIC GENERATION .2.

The synthesis and non-linear optical properties of a series of icosahedral carboranes are described. The carboranes are substituted on both carbon atoms, with a series of electron-donating and electron-withdrawing substituents. The single-crystal X-ray structure of two of the series 1,2-bis(3-nitrophenyl)-1,2-dicarba-closo-dodecaborane(12), 1, and 1-(3-nitrophenyl)-2-(4-nitrophenyl)-1,2-dicarba-closo-dodecaborane, 3, are presented. 3 crystallises in the space group P1BAR, with four molecules per unit cell with cell dimensions of a = 9.706(1) angstrom, b = 13.798(2) angstrom, c = 17.99(2) angstrom, alpha = 109.17(1)degrees, beta = 100.86(1)degrees and gamma = 101.78(1)degrees. 1 crystallises in the space group P1BAR, with two molecules per unit cell with cell dimensions of a = 7.585(2) angstrom, b = 11.032(3) angstrom, c = 12.252(4) angstrom, alpha = 105.29(3)degrees, beta = 90.30(3)degrees and gamma = 96.46(2)degrees. The second-harmonic generation (SHG) properties of all of the compounds prepared are described, and are related to the ZINDO-SOS calculations of molecular polarisibility, beta, computed for selected examples.