Synthesis and crystal structure of the fluoride-ammine complexes Zr(NH3)F4 and Hf(NH3)F4

Article abstract of DOI:10.1002/zaac.19976230114

Colourless, easily cleavable single crystals of Zr(NH₃)F₄ and Hf(NH₃)F₄ without special shape are obtained by oxidation of zirconium and hafnium metal powder with NH₄HF₂ (molar ratio 1:2) in sealed Monel ampoules at reaction temperatures of 380-450 °C. The two fluoride-ammine complexes crystallize isotypically in the triclinic space group P1 (no. 2) with a = 601.4(1)/597.8(8) pm [Zr(NH₃)F₄/Hf(NH₃)F₄], b = 802.8(2)/800.6(12) pm, c = 862.3(2)/860.8(8) pm, α= 106.39(1)/106.19(10)°, β = 104.25(1)/104.51(9)°, γ = 106.83(1)/106.69(11)°, Z = 4. Bicapped trigonal prisms [M(NH₃)F₇] are connected via edges and corners to form corrugated layers that are held together by hydrogen bonding.