Soluble Pyridine Complexes of the Ternary Gallium(III) Chalcogenide Halides (GaEX)₃, with E = S, Se and X = Cl, Br

The four ternary gallium(III) chalcogenide halides GaEX with E = S, Se and X = Cl, Br can be prepared a) from the binary gallium(III) chalcogenides Ga₂E₃ and halides Ga₂X₆, b) from gallium(I) tetrahalogallates(III) Ga[GaX₄] and the chalcogen E, and c) from gallium metal and the dichalcogen dihalides E₂X₂. The new method c) was shown to be the most convenient preparation. The products are readily soluble in pyridine to give trinuclear molecular complexes [GaEX·Py]3 which are not volatile without decomposition, but can be purified by crystallization. The structures have been determined by single crystal X-ray diffraction techniques. The two chlorides are isostructural and show twisted tub-form six-membered ring molecules with the pyridine donors in axial positions. The two bromides are also isostructural, but with the pyridine ligands in two axial and one equatorial positions.