COMBINING CARBABORANES WITH TRANSITION-METAL CLUSTERS - SYNTHESIS ANDX-RAY STRUCTURE-ANALYSIS OF A 5-PENTAMETHYL-2,3,4,5-TETRACARBA-NIDOHEXABORANE(6) DERIVATIVE

The 6-bromopentamethyl- and -3,4-diethyl-2,3,4,5-tetracarba-nidohexabo ranes(6) (1 and 2) react with the tetrahedrane anion [Fe-2(CO)(6)(mu-S N)](-) 3 to form the -nido-hexaborane(6)-yl]}hexacarbonyldiferraazathi a tetrahedranes 4 and 5, respectively, in which two different cages ar e directly connected through a B-N bond; the X-ray crystal structure o f 4 provides the first example of the structure of an 'undisturbed' 2, 3,4,5-tetracarba-nido-hexaborane(6).