Crystal growth in aqueous hydrofluoric acid and (HF)(x)center dot pyridine solutions: Syntheses and crystal structures of [Ni(H2O)(6)](2+)[MF(6)](2-) (M=Ti, Zr, Hf) and Ni-3(py)(12)F-6 center dot 7H(2)O

The syntheses and structures of [Ni(H2O)(6)](2+)[MF(6)](2-)(M = Ti, Zr, Hf) and Ni-3(py)(12)F-6 . 7H(2)O are reported. The former three compounds are isostructural, crystallizing in the trigonal space group <R(3)over bar> (No. 148) with Z = 3. The lattice parameters are a = 9.489(4), c = 9.764(7) Angstrom, with V = 761(1) Angstrom(3) for Ti;a = 9.727(2), c = 10.051 (3) Angstrom, With V = 823.6(6) Angstrom(3) for Zr; and a = 9.724(3), c = 10.028(4) Angstrom, with V = 821.2(8) Angstrom(3) for Hf. The structures consist of discrete [Ni(H2O)(6)](2+) and [MF(6)](2-) octahedra joined by O-H ... F hydrogen bonds. Large single crystals were grown in an aqueous hydrofluoric acid solution. Ni-3(PY)(12)F-6 . 7H(2)O crystallizes in the monoclinic space group I2/a (No. 15) with Z = 4. The lattice parameters are a = 16.117(4), b = 8.529(3), c = 46.220(7) Angstrom, beta = 92.46(2)degrees, and V = 6348(5) Angstrom(3). The structure consists of discrete Ni(py)(4)F-2 octahedra linked through H-O-H ... F and H-O-H ... O hydrogen bonding interactions. Single crystals were grown from a (HF)(x) . pyridine/pyridine/water solution.