PbF[Br2F7], a Fluoridobromate(III) of a p-Block Metal

Abstract

The compound PbF[Br2F7] represents the first fluoridobromate(III) of a p-block element. It was synthesized in form of needle-shaped crystals among its colorless powder from the direct reaction of PbF2 with BrF3. Powder X-ray diffraction, IR and Raman spectroscopy show that it was obtained in almost pure form with Pb3F8 and Pb2F6 as by-products. The single crystal structure was determined by X-ray diffraction. PbF[Br2F7] crystallizes in space group P21/c (No. 14) with a = 4.3698(3), b = 13.3767(7), c = 12.0836(8) Å, β = 97.509(5)°, V = 700.27(8) Å3, Z = 4 at T = 100 K. PbF[Br2F7] decomposes above 50 °C due to loss of BrF3 and pure PbF2 remains. Quantum chemical calculations were performed on the crystal structure of the compound to assign the bands of the vibrational spectra and to obtain electron density difference maps that visualize the electron density around the Pb atoms. CHARDI calculations support the assignment of the oxidation states +II, +III, and –I to the Pb, Br, and F atoms, respectively.