Syntheses, structure, and reactivity of 2,6-dimesitylphenyl-based sterically demanding gallium aryls

Reaction of gallium chloride with (2,6-dimesitylphenyl)lithium, (Mes(2)C(6)H(3))Li (Mes = 2,4,6-Me3C6H2), gives bis[(dimesitylphenyl)gallium dichloride], [(Mes(2)C(6)H(3))GaCl2](2), I. Treatment of I with {2-[(dimethylamino)methyl]phenyl}lithium [2-(Me2NCH2)C6H4]Li, affords (dimesitylphenyl)-2-((dimethylamino)methyl) chloride, (Mes(2)C(6)H(3))[2-(Me2NCH2)C6H4]GaCl, II. Reaction of (Mes(2)C(6)H(3))Li with gallium bromide affords bis(dimesitylphenyl)gallium bromide, (Mes(2)C(6)H(3))(2)GaBr, III, while reaction of I with (Mes)Li yields (dimesitylphenyl)dimesitylgallium, (Mes(2)C(6)H(3))(Mes)(2)Ga, IV. GalIium aryls I-IV have been characterized by elemental analyses, H-1 and C-13 NMR and IR spectroscopies, and single-crystal X-ray diffraction. I assumes a mu(2)-chloro-bridged dimeric structure, while the coordination of gallium in II is completed by one Mes(2)C(6)H(3) Ligand and one chloride ligand and is intramolecularly stabilized by the nitrogen atom of [2-(Me2NCH2)C6H4]. III assumes a rare T-shaped coordination about the gallium center (C-Ga-C 153.5(2)degrees), while TV represents, arguably, the most sterically crowded trigonal planar gallium aryl reported with the aromatic rings about the GaC3 plane approaching 90 degrees.