Use of dipole moments to determine the structure of halogen derivatives of ortho-and meta-carboranes

The crystal and molecular structure of tribromo-m-carborane

“…A later study yielded charges of -0.25 for B(9) and B(10), -0.06 for B(5) and B(12), -0.03 for B(4), B(6), B (8), and B (11), and f0.13 for B(2) and B(3) (26). It has been shown that the electrophilic chlorination and bromination occurs first at the B(9) and B (10) in HZ-carborane and its C-methyl derivatives (2,3,7,15,16,18,22,23,26,(29)(30)(31)(32)(33)(34)(35). However, the third bromine substituent could occupy either the B(5 or 12) or B(4, 6, 8, or 1 I) since molecular orbital calculations and simple inductive rule give very similar framework charges.…”