BrF5 can be prepared by treating BrF3 with fluorine under UV light in the region of 300 to 400 nm at room temperature. It was analyzed by UV-Vis, NMR, IR and Raman spectroscopy. Its crystal structure was redetermined by X-ray diffraction, and its space group was corrected to Pnma. Quantum-chemical calculations were performed for the band assignment of the vibrational spectra. A monoclinic polymorph of BrF5 was quantum chemically predicted and then observed as its low-temperature modification in space group P21 /c by single crystal X-ray diffraction. BrF5 reacts with the alkali metal fluorides AF (A=K, Rb) to form alkali metal hexafluoridobromates(V), A[BrF6 ] the crystal structures of which have been determined. Both compounds crystallize in the K[AsF6 ] structure type (R , no. 148, hR24). For the species [BrF6 ]+ , BrF5 , [BrF6 ]- , and [IF6 ]- , the chemical bonds and lone pairs on the heavy atoms were investigated by means of intrinsic bond orbital analysis.
Keywords: bromine pentafluoride; crystal structure; hexafluoridobromate; photochemistry; quantum-chemical calculations.
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