The crystal and molecular structure of tribromo-m-carborane

Abstract

The sequence of electrophilic substitution for o- and m-carborane has been the subject of much experimental and theoretical work. The molecular structure of tribromo-m-carborane (m-B10Br3H7C2H2) shows that the third bromine atom to be substituted is found bonded to boron atom 12 (or 5). The crystal data are: space group, Pbcm; a = 8.47(4), b = 12.19(8), and c = 12.25(8) Å; ρo = 1.98(2) and ρc = 2.00 g/cm3 for Z = 4. Data were collected using Weissenberg geometry and Ni-filtered CuK, radiation. The visually estimated intensities of 920 reflections were used in the anisotropic block-diagonalized least-squares refinement of the 76 structural parameters. The final value of the conventional residual index was 0.087.

Synthesis and Crystal Structure of 9,12-Dibromo-ortho-Carborane

“…Despite the fact that the bromination of orthoand meta-carboranes was first described back in the mid-1960s [44], neither the yield of bromination products nor their characterization (with the exception of X-ray diffraction data for crystals from the same syntheses [50][51][52][53]) have been described until recently. For the sake of fairness, it is worth noting an attempt to characterize the obtained bromo derivatives of ortho-carborane using 11 B NMR spectroscopy, however, due to the very limited instrumental capabilities of that time, at the present it is rather of historical interest [54].…”