SYNTHESIS AND CRYSTAL-STRUCTURE OF THE FL UORIDE-AMMINE COMPLEXES ZR(NH3)F-4 AND HF(NH3)F-4

Colourless, easily cleavable single crystals of Zr(NH3)F-4 and Hf(NH3) F-4 without special shape are obtained by oxidation of zirconium and h afnium metal powder with NH4HF2 (molar ratio 1:2) in sealed Monel ampo ules at reaction temperatures of 380-450 degrees C. The two fluoride-a mmine complexes crystallize isotypically in the triclinic space group P1 (no. 2) with a=601.4(1)/597.8(8) pm [Zr(NH3)F-4/Hf(NH3)F-4], b = 80 2.8(2)/800.6(12) pm, c = 862.3(2)/860.8(8) pm, alpha = 106.39(1)/106.1 9(10)degrees, beta = 101.25(1)/104.51(9)degrees, gamma = 106.83(1)/106 .69(11)degrees, Z = 4. Bicapped trigonal prisms [M(NH3)F-7] are connec ted via edges and corners to form corrugated layers that are held toge ther by hydrogen bonding.