Two anionically derivatized scandium oxoselenates(TV): ScF[SeO3] and Sc2O2[SeO3]

Scandium fluoride oxoselenate(IV) ScF[SeO3] and scandium oxide oxoselenate(IV) Sc2O2[SeO3] could be synthesized through solid-state reactions. ScF[SeO3] was obtained phase-pure, by reacting mixtures of Sc2O3, ScF3 and SeO2 (molar ratio: 1:1:3) together with CsBr as fluxing agent in corundum crucibles embedded into evacuated glassy silica ampoules after firing at 700 degrees C for seven days. Sc2O2[SeO3] first emerged as by-product during the attempts to synthesize ScCl[SeO3] following aforementioned synthesis route and could later be reproduced from appropriate Sc203/SeO3 mixtures. ScF[SeO3] crystallizes monoclinically in space group P2(1)/m with a=406.43(2), b =661.09(4), c=632.35(4) pm, beta=93.298(3)degrees and Z=2. Sc2O2[SeO3] also crystallizes in the monoclinic system, but in space group P2(1)/n with a=786.02(6), b=527.98(4), c=1086.11(8) pm, beta=108.672(3)degrees for Z=4. The crystal structures of both compounds are strongly influenced by the stereochemically active lone pairs of the-4,1-tetrahedral [SeO3](2-) anions. They also show partial structures, where the derivatizing F- or O2- anions play an important role. For ScF[SeO3] chains of the composition (1)(infinity)[FSc2/2](2+)} form from connected [FSc2](5+) dumbbells, while [OSc3](7+) pyramids and [OSc4](10+) tetrahedra units are condensed to layers according to (2)(infinity){[O2Sc2](2+)} in Sc2O2[SeO3].