The nature of subvalent gallium and indium in aqueous media

Subvalent gallium can exist in aqueous solutions as GaGa bonded gallium(II) species stabilised by halide ligands in the form of the complex anions Ga 2X 6 2− (X=Cl, Br or I) whose formation and reactivity are discussed. Gallium(I) compounds and mixed valence compounds of gallium react vigorously with water, converting any Ga + ions into Ga(III) products. Indium(I) is more tolerant of water, so that perchlorate and other non-complexing aqueous media can support In + ions at concentrations up to 10 −3 mol l −1 before disproportionation to In(0) and In(III) occurs. Subvalent indium concentrations of approximately 10 −1 mol l −1 are attained in halogen acid solution, particularly HBr which yields red, solid InBr upon dilution. Spectroscopic data suggest the precursor is an In(II)In(II) bromide complex (probably In 2Br 6 2− ) capable of breaking up into In(I) and In(III) products. Subvalent gallium can exist in aqueous solutions as GaGa bonded gallium(II) species stabilised by halide ligands in the form of the complex anions Ga 2X 6 2− (X=Cl, Br or I) whose formation and reactivity are discussed. Gallium(I) compounds and mixed valence compounds of gallium react vigorously with water, converting any Ga + ions into Ga(III) products. Indium(I) is more tolerant of water, so that perchlorate and other non-complexing aqueous media can support In + ions at concentrations up to 10 −3 mol l −1 before disproportionation to In(0) and In(III) occurs. Subvalent indium concentrations of approximately 10 −1 mol l −1 are attained in halogen acid solution, particularly HBr which yields red, solid InBr upon dilution. Spectroscopic data suggest the precursor is an In(II)In(II) bromide complex (probably In 2Br 6 2− ) capable of breaking up into In(I) and In(III) products.