Composition space of the (CuO, 1/2Nb(2)O(5))/(HF)(x)center dot pyridine/H2O system. Structure and synthesis of [pyH(+)](2)[CuNb2(py)(4)O2F10](2-) and CuNb(py)(4)OF5

Single crystals of [pyH(+)](2)[CuNb2(py)(4)O2F10](2-) and CuNb(py)(4)OF5 were synthesized in a (HF)(x) . pyridine/pyridine/water solution (150 degrees C, 24 h, autogenous pressure) using CuO and Nb2O5 as reagents. The compound [pyH(+)](2)[CuNb2(py)(4)O2F10](2-) contains clusters of [CuNb2(PY)(4)O2F10](2-) anions linked through N-H+... F hydrogen bonds to the [pyH(+)] cations. In contrast CuNb(py)(4)OF5 is a unidimensional compound consisting only of chains, perpendicular to the c axis, of alternating [Cu(py)(4)(O/F)(2/2)](0.5+) and [NbF4(O/F)(2/2)](0.5-) octahedra. The chains change direction between the [110] and [110] every c/2. Crystal data for [pyH(+)](2) [CuNb2(py)(4)O2F10](2-): tetragonal, space group I4(I)22 (No. 98),with a = 11.408(3) Angstrom, c = 30.36(1) Angstrom, and Z = 4. Crystal data for CuNb(py)(4)OF5: monoclinic, space group C2/c (No. 15), with a = 10.561(3) Angstrom, b = 13.546(6) Angstrom, c = 16.103(4) Angstrom, beta = 97.77(2)degrees, and Z = 4.