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1726673 
Journal Article 
A new rare-earth metal(III) fluoride oxoselenate(IV): YF[SeO3] 
Lipp, C; Schleid, T 
2008 
1 
Zeitschrift fuer Anorganische und Allgemeine Chemie
ISSN: 0044-2313 
634 
4 
657-661 
WOS:000254263900012 
Just two representatives of the rare-earth metal(III) fluoride oxoselenates(IV) with the formula type MF[SeO3] (M = La and Lu) exist so far, whereas for the intermediate lanthanoids only M3F[SeO3](4)-type Compounds (M = Gd and Dy) were accessible. Because of the similar radius of Y3+ to the radii of the heavier lanthanoid cations, a missing link within the MF[SeO3] series could be synthesized now with the example of yttrium(III) fluoride oxoselenate(IV). Contrary to LuF[SeO3] with its triclinic structure, YF[SeO3] crystallizes monoclinically in space group P2(1)/c (no. 14, a = 657.65(7), b = 689.71(7), c = 717.28(7) pm, beta = 99.036(5)degrees and Z = 4). A single Y3+ cation occupying the general site 4e is Surrounded by six oxide and two fluoride anions forming [YO6F2](11-) polyhedra (d(Y-O) = 228-243 plus 263 pm, d(Y-F) = 219-220 pm). These are linked via common O center dot center dot center dot O edges to (1)(infinity){[(YO4/2O2/1F2/1t)-O-e-F-t](7-)} chains running along [010] and adjacent chains get tied to each other by sharing common O3 center dot center dot center dot O3 and O3 center dot center dot center dot F edges which results in (2)(infinity){[Y(O3)(3/3)(O2)(2/2)(O1)(1/1)F-2/2](4-)} sheets parallel to (100). The Se4+ cations connect these (2)(infinity){[YO3F](4-)} sheets as psi(1)-tetrahedral [SeO3](2-) anions (d(Se-O) = 168-174 pm) for charge balance via all oxygen atorns. Despite the different coordination numbers of seven and eight for the rare-earth metal(III) cations the structures of LuF[SeO3] and YF[SeO3] appear quite similar. The (1)(infinity)[(LuO4/2O1/1F2/1t)-O-e-F-t](5-)} chains containing pentagonal bipyrarnids [LuO5F2](9-) are connected to (2)(infinity){(LuO4/2O1/1F2/2e)-O-e-F-t](4-)} layers running parallel to the (100) plane again. In fact it is only necessary to shorten the partial structure of the straight (1)(infinity)[LuF2/2](2+)} chains along [001] to achieve the angular (1)(infinity)[YF2/2](2+)} chains in YF[SeO3]. As a result of this shortening one oxide anion at a time moves into the coordination sphere of a neighboring y(3+) cation and therefore adds up the coordination number for y(3+) to eight. For the synthesis of YF[SeO3] yttrium sesquioxide (Y2O3) yttrium trifluoride (YF3) and selenium dioxide (SeO2) in a molar ratio of 1 : 1 : 3 with CsBr as fluxing agent were reacted within five days at 750 degrees C in evacuated graphitized silica ampoules. 
rare-earth metals; yttrium oxoselenates(IV); fluorides; crystal structures