Disproportionation of low valent indium bromide: Synthesis and molecular structure of bis(2,6-dimesityl-phenyl) indium bromide, (2,6-Mes(2)C(6)H(3))(2)InBr (Mes=2,4,6-Me3C6H2). When does trigonal planar become T-shaped?

Bis(2,6-dimesitylphenyl) indium bromide, (2,6-Mes(2)C(6)H(3))(2)InBr (Mes=2,4,6-Me3C6H2), I, has been prepared and characterized by H-1 NMR, elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. I may be approached by either of two synthetic routes. Whereas I may be readily prepared from reaction of indium (III) bromide with (2,6-dimesitylphenyl) lithium in Et2O, it may also be approached by an interesting disproportionation of Br2In-InBr2 in the presence of (2,6-Mes(2)C(6)H(3)) Li. The title compound crystallizes in the monoclinic space group P2(1)/n (No. 14) with unit cell parameters a=12.341 ((2)Angstrom, b=20.799 (4) Angstrom, c=16.512 (2) Angstrom, beta=101.18 (1)degrees, D-calcd=1.31 g cm(-3), and V=4158 (1)A(3) for Z=4. Refinement, based on 1661 observed reflections, converged at R=0.072, R-w=0.071. The In-Br bond distance is 2.505 (4) Angstrom. As the steric demands of the two bulky ligands are sufficient to result in a C-In-C bond angle of 157.3 (8)degrees-the widest angle reported for a three-coordinate indium atom-the coordination about the metal center may be described as T-shaped.