Synthesis and structure of halogen derivatives of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-Me2S-7,8-C2B9H11]

Halogenation of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-SMe2-7,8-C2B9H11] with N-chlorosuccinimide, bromine and iodine gave the expected corresponding halogen derivatives [9-SMe2-11-X-7,8-C2B9H10], where X = Cl (1), Br (2), I (3). In the bromination reaction, [9-SMe2-6-Br-7,8-C2B9H10] (4) was isolated as a minor product being the first example of substitution at a “lower” belt of the 7,8-dicarba-nido-undecaborate cage. The use of excess of bromine resulted in dibromo derivative [9-SMe2-6,11-Br2-7,8-C2B9H9] (5). Structures of the compounds prepared were determined using 11B–11B COSY NMR spectroscopy (for all halogen derivatives) and single crystal X-ray diffraction (for compounds 2, 3, and 5).