CHEMISTRY OF C-TRIMETHYLSILYL-SUBSTITUTED HETEROCARBORANES .16. SYNTHESIS AND CRYSTAL-STRUCTURE OF A DISCRETE, ZWITTERIONIC, MONOMERIC MONOSODIUM SALT OF 2,3-DICARBA-NIDO-HEXABORATE(1-) - CONVERSION TO THE 1STCARBONS ADJACENT DISODIUM COMPOUND

A TMEDA-solvated, zwitterionic monosodium salt, ,5-[(mu-H)2Na(TMEDA)2] -2-(SiMe3)-3-(Me)-2,3-C2B4H5 (II), was prepared and characterized by H -1, B-11, and C-13 NMR spectra, IR spectra and X-ray crystallography. The presence of an exposed B-H-B bridge hydrogen on the open C2B3 face of the carborane in the discrete monomeric unit allowed II to undergo further deprotonation by NaH to produce, in 94% yield, the first diso dium compound of the 2,3-C2B4 carborane (carbons adjacent) dianion, a- (TMEDA)]-1-Na(TMEDA)-2-(SiMe3)-3-(Me)-2,3-C2B4H4 (III).