Laval Jean Paul, Jennene Boukharrata Nefla
Science des Procédés Céramiques et de Traitements de Surface, UMR-CNRS 6638, Faculté des Sciences et Techniques, Université de Limoges, 123 Avenue A. Thomas, Limoges 87060, France.
Acta Crystallogr C. 2008 Jul;64(Pt 7):i47-9. doi: 10.1107/S0108270108007087. Epub 2008 Jun 7.
As an extension of a general structural study concerning fluorides and oxyfluorides of cations presenting a stereochemically active electronic lone pair, until now limited to tellurium(IV) phases, the previously unknown structure of NaIO(2)F(2) corresponds to a new structure type based on isolated IO(2)F(2)(-) polyhedra forming sheets separated by Na(+) layers. The sodium ion is octahedrally coordinated with 2/m site symmetry, while the I(V) atom has m2m symmetry with a stereochemically active lone electron pair. The O and F atoms (both with m symmetry) are bonded to the I(V) atoms in a fully ordered manner. A comparison with the structure of ferroelastic KIO(2)F(2) and with structures based on hexagonal close packing of anions, mainly rutile-type and FeTeO(3)F-type, reveals differences that are attributed to the smaller ionic radius of Na(+) and the ordering of the Na and I cations.
作为关于具有立体化学活性电子孤对阳离子的氟化物和氟氧化物的一般结构研究的扩展，此前该研究仅限于碲（IV）相，至今未知的NaIO₂F₂结构对应于一种基于孤立的IO₂F₂⁻多面体形成的新结构类型，这些多面体形成的片层被Na⁺层隔开。钠离子以2/m点群对称性呈八面体配位，而I（V）原子具有m2m对称性且有一个立体化学活性的孤电子对。O和F原子（均具有m对称性）以完全有序的方式与I（V）原子键合。与铁弹性KIO₂F₂的结构以及基于阴离子六方密堆积的结构（主要是金红石型和FeTeO₃F型）进行比较，发现差异归因于Na⁺较小的离子半径以及Na和I阳离子的有序排列。
