Synthesis and molecular structures of the 1,2-dihalogen derivatives of Ga(II) and In(II), [{GaI(ArMe6)}2], [{InCl(ArMe6)}2]2, [{InI(ArMe6)}2]2, and [{In4Cl2I2(ArMe6)4}], ArMe6C6H3-2,6(C6H2-2,4,6-Me3)2

The reaction of LiArMe6 [ArMe6C6H3-2,6(C6H2-2,4,6-Me3)2] with InCl, [In(InI4)], InCl in the presence of LiI, or ‘GaI’ in toluene solution resulted in the isolation of the 1,2-diaryl-1,2-dihalogen derivatives [{InCl(ArMe6)}2]2 (1), [{InI(ArMe6)}2]2 (2), [{In4Cl2I2(ArMe6)4}] (3), and [{GaI(ArMe6)}2] (4). The indium derivatives 1–3 were isolated as tetrametallic complexes formed via the almost symmetric bridging by four halides of two In–In bonded, ArMe6In–InArMe6 moieties. In 1, the In4Cl4 core features almost parallel In–In units, linked by four almost symmetrically bridging chlorides. This yields a structure formed from two folded In2Cl2 rings, and two six-membered In4Cl2 boat-shaped rings that have common In–Cl edges. The structures of 2 and 3 also feature two ArMe6InInArMe6 units bridged by four halides. However, there is a large torsion angle between the two In–In vectors, so that the In4I4 (2) and In4Cl2I2 (3) cores are formed from four five-membered In3I2 (2) or In3ClI (3) rings. Compound 4 has a simple Ga–Ga bonded dimeric structure, in which the gallium atoms are three coordinated, being bonded to each other as well as to an iodine and an ArMe6 ligand. All the compounds were characterized by 1H and 13C {1H} NMR spectroscopy, and by X-ray crystallography. The structural differences between the gallium and indium derivatives is probably a result of the larger size and greater Lewis acidity of the indium centers.

The associated 1,2-dihalo-1,2-diaryl diindium(I) dimeric compounds shown in the drawing, in which the indiums are four coordinate, have different structures for the chloride and iodide salts. In contrast, the corresponding 1,2-diiodo-1,2-diaryl digallium(II) compound is monomeric with three coordinated gallium atoms.Figure optionsDownload as PowerPoint slide