Fcu[AuF₄], an Unusual Copper(II) Fluoroaurate(III)^†

The title compound, a ternary fluoride of two coinage metals, has unusual composition, structure, and magnetic properties. The kind and extent of Jahn-Teller distortion for Cu²⁺ are unexpected; the coordination number for Cu²⁺ is 2 + 2 + 2 = 6, while gold, on the other hand, shows the usual squareplanar coordination for Au³⁺-compounds. The compound is antiferromagnetic; the one-dimensional, magnetic interaction takes place along the linear Cu-F chains parallel to [001].