Synthesis, Structure, and Spectroscopic Properties of the New Lanthanum(III) Fluoride Oxomolybdate(VI) La₃FMo₄O₁₆

Abstract

2-units, a fourth one with a higher coordination number (CN = 4 +1) can be found in the crystal structure, forming a dimeric entity with a for-

Press to Success: Gd5FW3O16—The First Gadolinium(III) Fluoride Oxidotungstate(VI)

“…Both the Gd 3+ -O 2− distances of 219-295 pm and the Gd 3+ -F − distances of 230-236 pm ( Table 3) Table 4). A very similar environment of the fluoride anions is found in the crystal structure of the lanthanum(III) fluoride oxidomolybdate(VI) of the composition La 3 FMo 4 O 16 [24], in which the La-F-La bond angles range between 108 and 137 • and the deviation of the fluoride atoms out of the plane built up by La 3+ cations is about 24 pm. For (Gd5) 3+ , a rather high and very prolate displacement ellipsoid is noticeable (see Figure 3 bottom left), which can be explained by an anisotropic distribution of the distances between these cations and their surrounding oxide ligands.…”

“…Inspired by single crystals of two RE(OH) [WO 4 ] derivatives, which occurred during high-pressure experiments to obtain RE 3 Cl 3 [WO 6 ] representatives of the smaller rare-earth metals [22,23], the high-pressure synthesis of the formula analogous, and presumably pseudo-isotypic (due to the replacement of OH − by F − ) REF [WO 4 ] derivatives, was pursued. Although, the desired products could not be yielded, it was possible to obtain very few single crystals of the gadolinium(III) fluoride oxidotungstate(VI) with the composition Gd 5 FW 3 O 16 comprising two different ditungstate units as well as [FGd 3 ] 8+ entities -a structural motif known also from La 3 FMo 4 O 16 [24] and other fluoride-containing lanthanoid compounds. Hence, the high-pressure synthesis route opens up a possibility to obtain fluoride-containing rare-earth metal(III) oxidotungstates(VI), which may provide suitable host lattices for luminescent cations, e.g., Eu 3+ and Tb 3+ , as dopants for compounds of the luminescent innocent rare-earth metals yttrium, lanthanum, gadolinium, and lutetium, analogous to the molybdates, e.g., YF[MoO 4 ]:Eu 3+ [13].…”

Syntheses, Crystal Structures, and Twinning of the Isotypic Rare‐Earth Metal Bromide Ortho‐Oxidomolybdates LaBrMoO4 and CeBrMoO4

“…While fluoride examples with the formula RE F[MoO 4 ] have only been observed for the smaller metal trications ( RE = Y,1 Sm – Tm2), the RE Cl[MoO 4 ] representatives were obtained throughout the complete rare‐earth metal series3 ( RE = Y,1 La – Pr,4 Nd,5 Sm – Lu6). Besides the aforementioned compounds, only the fluoride poor compound La 3 F[MoO 4 ] 4 has found entry into literature7. Bromide and iodide derivatives have been unknown so far, except for YBr[MoO 4 ]8.…”

Syntheses and Crystal Structures of the Bromide-derivatized Lanthanoid(III) Ortho-Oxomolybdates(VI) LnBr[MoO4] (Ln = Pr, Nd, Sm, Gd– Lu)

“…Similar [MoO 5 ] 4− polyhedra are also found in the rare earth metal(III) chloride oxomolybdates(VI) with the formula LnCl [MoO 4 ] (Ln = La -Pr) [4] as well as their bromide homologs LnBr [MoO 4 ] (Ln = La and Ce) [5]. While in La 3 F[MoO 4 ] 4 [3] the halide anion is coordinated by only three La 3+ cations, this coordination number increases to three plus one in the aforementioned compounds REX [MoO 4 ] comprising only the largest rare earth metals. Furthermore, in all these structures the coordination spheres of the RE 3+ cations consist of nine or even nine plus one oxide and halide anions, and are thus considerably larger than those with coordination numbers of seven or eight as found in the halide derivatives with the formula REX [ …”

“…All of them show a structural gap between the lighter and the heavier lanthanides (plus yttrium). The rare earth metal(III) fluoride oxomolybdates(VI) with the formula REF [MoO 4 ] are only known for yttrium and the heavier cations (RE = Y [1], Sm -Tm [2]) so far, while for the lighter lanthanide elements only the fluoride-poor compound La 3 F[MoO 4 ] 4 [3] has been structurally characterized. Its structure comprises the halide anion surrounded by three La 3+ cations and besides, three crystallographically independent, but isolated [MoO 4 ] 2− tetrahedra, and another one with a coordination number of four plus one is observed as a trigonal-bipyramidal [MoO 4+1 ] 4− unit.…”