[pyH]₂[Cu(py)₄(MX₆)₂] (MX₆ = ZrF₆²⁻, NbOF₅²⁻, MoO₂F₄²⁻; py = Pyridine):  Rarely Observed Ordering of Metal Oxide Fluoride Anions

Single crystals of [pyH](2)[Cu(py)(4)(MX(6))(2)] (MX(6) = ZrF(6)(2)(-), MoO(2)F(4)(2)(-); py = pyridine), analogous to those of the previously reported [pyH](2)[Cu(py)(4)(NbOF(5))(2)], were synthesized by reaction of the metal oxides in (HF)(x)().pyridine/pyridine/water solutions (150 degrees C, autogeneous pressure). The NbOF(5)(2)(-) and MoO(2)F(4)(2)(-) anions generally crystallize with orientational disorder masking the true coordination geometry. The combination of the two different and strongly coordinating cations tetrakis(pyridine)copper(II) and pyridinium causes the anions to adopt regular and ordered orientations. Crystal data: for [pyH](2)[Cu(py)(4)(ZrF(6))(2)], tetragonal, space group I4/mmm (No. 139), with a = 11.047(1) Å, c = 16.763(3) Å, and Z = 2; for [pyH](2)[Cu(py)(4)(MoO(2)F(4))(2)], monoclinic, space group C2/c (No. 15), with a = 19.195(4) Å, b = 11.316(3) Å, c = 18.920(5) Å, beta = 107.68(2) degrees, and Z = 4.