Preparation of Two Quantum-Chemically Predicted, Isomeric [Br4F13]- Anions in the Solid State

Two isomeric tridecafluoridotetrabromate(III) anions, [Br4F13](-), both previously predicted by quantum-chemical calculations, have serendipitously been obtained from the reaction of BrF3 with BaF2. Single crystals of Ba-2[Br3F10](2)[Br4F13](2) were selected from the reaction mixture at approximately 10 degrees C. The crystal structure contains two novel, isomeric [Br4F13](-) anions besides the known, star-shaped [Br3F10](-) anions. It crystallized in the monoclinic space group P1n1 (No. 7) with a = 8.8519(18), b = 15.217(3), c = 14.628(3) angstrom, beta = 90.34(3)degrees, V = 1970.4(7) angstrom(3) and Z = 2, mP124 at 100 K. The compound was additionally investigated using quantum-chemical solid-state calculations. If however crystals from the above reaction mixture were selected at room temperature, the compound Ba[Br3F10](2)center dot BrF3 was obtained containing disordered BrF3 molecules of crystallization besides [Br3F10](-) anions. The [Br4F13](-) molecules were no longer present. Ba[Br3F10](2)center dot BrF3 crystallized in the cubic space group Pa3 (No. 205) with a = 12.4903(14) angstrom, V = 1948.6(7) angstrom(3), Z = 4, cP124, T = 100 K. The much easier to handle latter compound was additionally investigated using powder X-ray diffraction, as well as IR and Raman spectroscopy.