THE CRYSTAL-STRUCTURE OF THE BINUCLEAR FLUOROCOMPOUND CS3GA2F9

The crystal structure of hexagonal Cs3Ga2F9 (a = 10.945 angstrom, c = 14.756 angstrom, rho = 4.61 g.cm-3, Z = 6, space group P6(3)cm) has be en determined using 1072 independent single crystal X-ray reflections (R = 0.030, wR = 0.036 ). The structure contains two independent binuc lear units Ga2F9 of strongly distorted face-sharing octahedra (d(Ga-Ga ) = 2.85 angstrom, average d(Ga-F) = 1.90 angstrom). The two units are in a 1 : 2 proportion and repeat each at c/2 along [001], but they ar e shifted with respect to each other by about c/6. The structure is co mpared with that of Cs3Fe2F9 and related compounds.