SYNTHESIS AND CHARACTERIZATION OF BULKY ARYL DERIVATIVES OF THE HEAVIER MAIN GROUP-3 ELEMENTS

The synthesis and structural characterization of several bulky aryl derivatives of aluminum, gallium, and indium are described. With the exception of the previously synthesized species Al(Mes)Cl2.THF (1) and [Ga(Mes)2Cl]2(6) (Mes = 2,4,6-Me3CrH2)the compounds are derivatives of the very crowding 2,4,6-i-Pr3CrH2- (Trip) or 2,4,6-t-BuC6H2- (Mes*) substituents, as indicated by the formulas Al(Trip)Br2(Et2O) (2), [Al(Trip)2Br]2 (3), Ga(TriP)Cl2.THF (4), [(Et2O)LiCl3Ga(Trip)]2 (5), Ga(TriP)2Cl (X = Cl (7), Br (8)), Ga(TriP)3 (9), Al(Mes*)Br2 (10), and M(Mes*)Cl2 (M = Ga (11), In (12)). The most interesting feature of these compounds is that, in several instances (7, 8, 10-12), previously unknown unassociated species can be obtained in the crystal phase with only partial substitution of the halides. In the case of compounds 10-12, uncomplexed monoaryl dihalide derivatives can be obtained even in the presence of ether. Thus, these compounds are useful precursors for the synthesis of other derivatives in which the presence of three-coordinate aluminum, gallium, or indium is desirable.