Synthesis, crystal structures and spectroscopic properties of pure YSb2O4Br and YSb2O4Cl as well as Eu3+- and Tb3+-doped samples.

The quaternary halide-containing yttrium(iii) oxidoantimonates(iii) YSb2O4Cl and YSb2O4Br were synthesised through solid-state reactions from the binary components (Y2O3, Sb2O3 and YX3, X = Cl and Br) at 750 °C in evacuated fused silica ampoules with eutectic mixtures of NaX and CsX (X = Cl and Br) as fluxing agents. YSb2O4Cl crystallizes tetragonally in the non-centrosymmetric space group P4212 with unit-cell parameters of a = 773.56(4) pm and c = 878.91(6) pm, whereas YSb2O4Br is monoclinic (space group: P21/c) with a = 896.54(6) pm, b = 780.23(5) pm, c = 779.61(5) pm and ß = 91.398(3)°, both for Z = 4. The two new YSb2O4X compounds contain [YO8]13- polyhedra, which are connected via four common edges to form layers (d(Y3+-O2-) = 225-254 pm) without any Y3+⋯X- bonds (d(Y3+⋯X-) > 400 pm). Moreover, all oxygen atoms belong to ψ1-tetrahedral [SbO3]3- units, which are either connected to four-membered rings [Sb4O8]4- in the chloride (Y2[Sb4O8]Cl2 for Z = 2) or endless chains in the bromide (Y1/2(SbO2)Br1/2 for Z = 8) by common vertices. With distances of 307 pm in YSb2O4Cl and 326 pm in YSb2O4Br there are not even substantial bonding Sb3+⋯X- (X = Cl and Br) interactions at work. Luminescence spectroscopy on samples doped with trivalent europium and terbium showed an energy transfer from the oxidoantimonate(iii) moieties as the sensitizer in the host structure onto the lanthanoid activators.

The very first normal-pressure tin borate Sn3B4O9, and the intermediate Sn2[B7O12]F.

Aside from amorphous phases, only a single crystalline tin borate had been synthesised so far under high pressure. In this work, we present the very first crystalline ternary tin borate Sn3B4O9 synthesised under ambient pressure by decomposition of Sn3[B3O7]F above 500 °C. The crystal structure of Sn3B4O9 (P21/c, Z = 4, a = 768.07(3) pm, b = 1206.78(4) pm, c = 924.96(3) pm, ß = 101.847(1)°, 10 550 data, 147 parameters, R1 = 0.028) determined by single-crystal X-ray diffraction comprises open layered borate polyanions with Sn(ii) ions in-between showing the presence of a stereochemically active lone pair. Sn3B4O9 was further characterized by DFT calculations and vibrational spectroscopy. Its optical band gap was calculated to approx. 3.5(1) eV. Tin borate was gained by thermal decomposition of Sn[B2O3F2] via a further new tin borate fluoride Sn2[B7O12]F (C2/c, Z = 8, a = 1037.99(2) pm, b = 859.78(2) pm, c = 2370.71(8) pm, ß = 93.5650(10)°, 2674 data, 199 parameters, R1 = 0.045).

The First Alkaline-Earth Fluorooxoborate Ba[B4 O6 F2 ]-Characterisation and Doping with Eu2.

The very first alkaline-earth fluorooxoborate Ba[B4 O6 F2 ] was synthesised by solid state methods starting from Ba(BF4 )2 , ß-BaB2 O4 , and B2 O3 . The crystal structure derived from single-crystal X-ray diffraction (P21 /n, a=6.6384(2) Å, b=7.6733(3) Å, c=11.3385(4) Å, ß=91.281(2)°, Z=4, Rint =0.0269, R1 =0.018, wR2 =0.034) comprises layers of BO3 F tetrahedra condensed through triangular BO3 units according to the descriptor 2Δ2□:<Δ2□>Δ. The extraordinary thirteen-fold coordination of barium by oxygen and fluorine leads to interesting optical properties of a sample doped with divalent europium, where a 4f→4f emission was recorded around 359 nm together with a broad emission band of a 5d→4f emission peaking at 366 nm. The compound is further characterised by IR-, Raman-, and solid-state NMR-spectroscopic methods. Moreover, DFT calculations as well as TGA and DSC measurements were performed.