The [Cu8Br15]6- Ion, A Crystal-Stabilized High-Symmetry Mixed-Valence Copper Complex with a Linear Halogen Bridge

The [Cu8Br15]6- ion in green crystalline (MePh3P)6[Cu8Br15] is shown by X-ray crystallography to have the structure [Br3(μ3-Br4Cu4)(μ2-Br)(μ3-Br4Cu4)Br3]6- derived from two Cu4Br8 cubane units. The unusual geometry and charge of the anion are determined by the high-symmetry (space group Pa3̄) lattice of cations, maintained by phenyl···phenyl interactions, and interacting with the anion by C−H···Br hydrogen bonds.