Willi Keller

2,4,6,8,9,10-Hexachlor-2,4,6,8,9,10-hexaboradamantan

The pyrolysis of alkyldichloroboranes such as MeBCl2BCHCHBCl2, Cl2BCH2BCl2 or (Cl2B)3CH at 450°C leads to the formation of hexachloro-hexaboraadamantane, C4H4B6Cl6 (I). The structure - determined by X-ray diffraction - and the spectroscopic data of 2,4,6,8,9,10-hexachloro-2,4,6,8,9,10-hexaboraadamantane are in agreement with the classical description as an organoborane, rather than as a molecule with a carborane framework. Substitution reactions are described. The bromo compound C4B4B6Br6 can be prepared by heating Me2BBr or MeBBr2 to 520°C.

Ein neuer Zugang zu halogenierten Carboranen

The copyrolysis of tetrahalogenodiborane(4) (B2X4, X = Cl, Br) or the halogenated carbon compounds such as CX4 or C2X4 yields the new carboranes C2B5X7 and C2B7Cl9 in addition to the vinyl compound C2Br3BBr2 as some of the products.

Indirect nuclear spin–spin coupling in tetrachlorotetraborane(4) and halogenated polyhedral phospha- and arsaboranes

The linewidths of 10B NMR signals of tetrachlorotetraborane (1), measured at various temperatures, indicate that there are weak scalar 11B–10B interactions. Selective homonuclear 11B{11B} decoupling experiments confirmed previous signal assignments and improved the resolution of 11B NMR spectra (by simplifying the complex spin systems) of closo‐diheteroboranes 1,2‐P2B4Cl4 (2), 1,2‐P2B4Br4 (3) and 1,2‐AsPB4Cl4 (4) and the icosahedral closo‐diheteroboranes 1,7‐P2B10Cl10 (6) and 1,7‐P2B10Br10 (7). This allowed the determination of coupling constants 1J(31P, 11B) of the order of 27–39 Hz, significantly smaller than for known non‐halogenated parent compounds. The 11B and 31P NMR spectra of 2, measured at 60 °C, allowed the determination of 1J(31P, 31B) = −100 ± 3 Hz by simulation. Copyright

Zwölfgliedrige Heteroborancluster durch Copyrolyse von Tetrachlordiboran(4) mit Elementhalogeniden/ Twelve-Vertex Heteroborane Clusters by Copyrolysis of Tetrachlorodiborane(4) and Element Halides

Abstract The perchlorinated arsaboranes closo-1,2-As2B10Cl10 and As4B8C16 are formed in the co pyrolysis of B2C14 and AsCl3 at temperatures of 330-450°C. The icosahedral structure of closo-1,2-As2B10Cl10 is confirmed by 11B-11B-COSY-NMR spectroscopy. As4B8Cl6 is suppo sed to be a conjuncto-borane (As2B4Cl3)2 with two boron-boron linked As2B4Cl3 octahedra. The copyrolysis of B2Cl4 andSbCl3 or SbCl5 yields Sb2B10Cl10, and the corresponding reaction of B2Cl4 with S2Cl2 gives the icosahedral thiaborane cluster SB11Cl11 .