The crystal and molecular structure of potassium monofluoroxenate(VI), KXeO3F, has been determined from three-dimensional X-ray data collected by counter methods. The material crystallizes in space group C2V9-Pn21a of the orthorhombic system with four molecules in a cell of dimensions a = 7.374 (5), b = 6.811 (5), c = 8.185 (6) Å. The calculated density is 3.835 g cm-3. Least-squares refinement of the structure has led to a final value of the conventional R factor (on F) of 0.054 for the 830 independent reflections having F2 ≥ 3 σ(F2). The crystal structure consists of infinite chains, parallel to the b axis, of XeO3 units linked by bridging fluorine atoms, with the potassium cations at nonbonded distances from the oxygen and fluorine atoms. The geometry of the XeO3 moiety is very similar to that of Xe03 itself. The Xe-O distances are 1.75 (1), 1.76 (1), and 1.79 (1) Å, and the O-Xe-O bond angles are 97.8 (7), 100.5 (1.2), and 101.1 (9)°. The two independent Xe-F distances of 2.36 (1) and 2.48 (1) Å are considerably longer than the distances reported for nonbridging Xe-F bonds but are significantly shorter than the value of 3.5 Å predicted for nonbonded interactions between Xe and F. Thus, the description of this compound as a molecular addition complex of formula K +F- XeO3 is incorrect, the correct formulation being nK+(XeO3F-)n.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry