Disproportionation of Low Valent Indium Bromide: Synthesis and Molecular Structure of Bis (2,6-Dimesityl-Phenyl) Indium Bromide, (2,6-Mes2C6H3)2InBr (Mes = 2,4,6-Me3C6H2). When does Trigonal Planar Become T-Shaped?
Affiliations: Department of Chemistry, The University of Georgia, Athens, GA 30602-2556 | Department of Chemistry, Clemson University, Clemson, SC 29634-1905
Note:  Corresponding Author
Abstract: Bis(2, 6-dimesitylphenyl) indium bromide, (2, 6-Mes2C6H3)2 InBr (Mes = 2, 4, 6-Me3C6H2), I, has been prepared and characterized by 1H 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-hBr2 in the presence of (2, 6-Mes2C6H3)Li. The title compound crystallizes in the monoclinic space group P21/n (No. 14) with unit cell parameters a = 12.341 ((2)Å, b = 20.799 (4) Å, c = 16.512 (2) Å, β = 101.18 (1)°, Dcalcd = 1.31 g cm−3, and V = 4158 (l)Å3 for Z = 4. Refinement, based on 1661 observed reflections, converged at R = 0.072, Rw = 0.071. The In-Br bond distance is 2.505 (4) Å. As the steric demands of the two bulky ligands are sufficient to result in a C-In-C bond angle of 157.3 (8)° — the widest angle reported for a three-coordinate indium atom — the coordination about the metal center may be described as T-shaped.