NEW FRONTIERS IN MAIN GROUP HETEROCARBORANES

The synthetic utility of the C2B4-carborane dianions in the preparation of a number of main group heterocarboranes is demonstrated. The closo-heterocarboranes from the donor-acceptor complexes with a variety of Lewis bases. The structures of the heterocarboranes and their complexes have been determined by X-ray diffraction. The common structural features of the donor-acceptor complexes are the longer M-C (M = heteroatom) bonds due to extreme slippage of the heteroatom toward the unique boron, and the orientation of the bonded base opposite the cage carbons. The exclusive formation of the stable, 1,2-isomer of the dicarba-closo-hexaborane (6) from C2B4-carborane dianions and closo-stannacarboranes is described. Synthesis and structural characterizations of closo-gallacarboranes and their donor-acceptor complexes are also presented.