PUB - Publikationen an der Universität Bielefeld

Gallium(I) tetrachlorogallate(III) Ga[GaCl4] was prepared in quantitative yield by thermal decomposition of dichlorogallane [HGaCl2](2), which is readily available from Et3SiH and [GaCl3]2. The reaction of catechol with solutions of this gallium(I) tetrachlorogallate(III) in tetrahydrofuran leads to the evolution of hydrogen gas and affords a dinuclear gallium(III) complex with penta-coordinate metal atoms chelated and bridged by mono-deprotonated catechol ligands. In the crystalline phase tetrahydrofuran molecules are hydrogen-bonded to the hydroxy groups: [Ga(1,2-OC6H4OH)Cl-2(C4H8O)](2). The reaction with pinacol also gives hydrogen and the analogous product [Ga(OCMe2CMe2OH)Cl-2(C4H8O)](2). The structures of the two compounds have been determined by X-ray diffraction. A mechanism of the new reaction has been proposed which involves oxidative addition of the diol to the solvate (THF)Cl2Ga-GaCl2(THF) present in the tetrahydrofuran solution to give a gallium hydride intermediate.