Composition Space of the (CuO, ¹/₂Nb₂O₅)/(HF)<i>_x</i>·pyridine/H₂O System. Structure and Synthesis of [pyH⁺]₂[CuNb₂(py)₄O₂F₁₀]^2- and CuNb(py)₄OF₅

Abstract

Single crystals of [pyH(+)](2)[CuNb(2)(py)(4)O(2)F(10)](2)(-) and CuNb(py)(4)OF(5) were synthesized in a (HF)(x)().pyridine/pyridine/water solution (150 degrees C, 24 h, autogeneous pressure) using CuO and Nb(2)O(5) as reagents. The compound [pyH(+)](2)[CuNb(2)(py)(4)O(2)F(10)](2)(-) contains clusters of [CuNb(2)(py)(4)O(2)F(10)](2)(-) anions linked through N-H(+).F hydrogen bonds to the [pyH(+)] cations. In contrast CuNb(py)(4)OF(5) 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 [NbF(4)(O/F)(2/)(2)](0.5)(-) octahedra. The chains change direction between the [110] and [1&onemacr;0] every c/2. Crystal data for [pyH(+)](2)[CuNb(2)(py)(4)O(2)F(10)](2)(-): tetragonal, space group I4(1)22 (No. 98),with a = 11.408(3) Å, c = 30.36(1) Å, and Z = 4. Crystal data for CuNb(py)(4)OF(5): monoclinic, space group C2/c (No. 15), with a = 10.561(3) Å, b = 13.546(6) Å, c = 16.103(4) Å, beta = 97.77(2) degrees, and Z = 4.