The [U₂F₁₂]^2- Anion of Sr[U₂F₁₂]

The D_2h-symmetric dinuclear complex anion [U₂F₁₂]^2- of pastel green Sr[U₂F₁₂] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge-linked monocapped trigonal prisms, the U^V atoms are therefore seven-coordinated. This leads to a U-U distance of 3.8913(6)Å. A weak U^V-U^V interaction is observed for the dinuclear [U₂F₁₂]^2- complex and described by the antiferromagnetic exchange J_exp of circa -29.9cm^-1. The crystalline compound can be easily prepared from SrF₂ and β-UF₅ in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X-ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid-state quantum chemical calculations.