Scheelite-type sodium neodymium(III) ortho-oxidomolybdate(VI), NaNd[MoO4]2

The crystal structure of Scheelite-type NaNd[MoO4]2 is described in the paper

Scheelite-type sodium neodymium(III) ortho-oxidomolybdate(VI), NaNd[MoO4]2

Scheelite-type NaNd[MoO4]2 contains one crystallographic position (site symmetry ) for the large cations, which is mixed-occupied by Na+ and Nd3+ cations in a 1:1 molar ratio. Thus, both are surrounded by eight O atoms in the shape of a trigonal dodeca­hedron. Furthermore, the structure consists of crystallographically unique [MoO4]2− units (site symmetry ) surrounded by eight sodium and neodymium cations, which are all vertex-attached. The polyhedra around the Na+/Nd3+ cations are connected to four others via common edges, building up a three-dimensional network in whose tetra­hedral voids of O atoms the Mo6+ cations reside

The defect scheelite-type lanthanum(III) ortho-oxidomolybdate(VI) La0.667[MoO4]

The crystal structure of La0.667[MoO4] in the Scheelite-type is described in that paper

the very different redox behaviour of isoelectronic complexes with [PtCl2] and [AuCl2]+

The new, potentially ambidentate heterocyclic ligand 2,3-bis(1-methylimidazol-2-yl)quinoxaline (bmiq) was obtained from 2,3-bis(1-methylimidazol-2-yl)glyoxal and 1,2-diaminobenzene. Its coordination to PtCl2 and to the isoelectronic [AuCl2]+ in [AuCl2(bmiq)](AuCl4) occurs via the imine N donors of the imidazolyl groups, leading to the formation of seven-membered chelate rings with boat conformation. According to the spectroelectrochemistry (UV-vis-NIR, EPR), the reversible electron addition to the [PtCl2(bmiq)] and the free ligand takes place in the (non-coordinated) quinoxaline part of the molecule, similarly as for related complexes of dipyrido[3,2-a:2′,3′-c]phenazines (dppz), 2,3-bis(2-pyridyl)quinoxalines (bpq) and 2,3-bis(dialkylphosphino)quinoxalines (QuinoxP). DFT calculations confirm the experimental results (structures, spectroscopy) and also point to the coordination potential of the quinoxaline N atoms. The electron addition to [AuCl2(bmiq)]+ takes place not at the ligand but at the metal site, according to experimental and DFT results

Defect scheelite-type lanthanoid(III) ortho-oxomolybdates(VI) Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and their relationship to zircon and the NaTl-type structure

The rare-earth metal(III) ortho-oxomolybdates with the formula Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and defect scheelite-type structure crystallize in the tetragonal space group I41/a (a = 533–525, c = 1183–1158 pm) with four formula units per unit cell. The Ln3+ cations at Wyckoff position 4b exhibit a coordination sphere of eight oxygen atoms in the shape of a trigonal dodecahedron. The same site symmetry ( 4 ..) is observed for the tetrahedral oxomolybdate(VI) entities [MoO4]2–, since their central Mo6+ cation is situated at the 4a position. Due to this equal site multiplicity, the lanthanoid(III) cations have to be statistically under-occupied to maintain electroneutrality, thus a defect scheelite structure emerges. The partial structure of both the Ln3+ cations and the [MoO4]2– anions (if shrunk to their centers of gravity) can be best described as distorted diamond-like arrangements. Therefore, these two interpenetrating partial structures exhibit a similar setup as found in the zircon-type as well as in the NaTl-type structure

Mixed occupancy: the crystal structure of scheelite-type LiLu[MoO4]2

Coarse colorless single crystals of lithium lutetium bis[orthomolybdate(VI)], LiLu[MoO4]2, were obtained as a by-product from a reaction aimed at lithium derivatives of lutetium molybdate. The title compound crystallizes in the scheelite structure type (tetragonal, space group I41/a) with two formula units per unit cell. The Wyckoff position 4b (site symmetry \overline{4}) comprises a mixed occupancy of Li+ and Lu3+ cations in a 1:1 ratio. In comparison with a previous powder X-ray study [Cheng et al. (2015). Dalton Trans. 44, 18078–18089.] all atoms were refined with anisotropic displacement parameters

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

The gadolinium(III) fluoride oxidotungstate(VI), with the formula Gd5FW3O16, represents the first published fluoride-derivative of a rare-earth metal oxidotungstate. It is synthesized by a mixture of GdF3, Gd2O3, and WO3 at 800 °C and a pressure of 2 GPa with the help of a belt press. The title compound crystallizes in the monoclinic space group P21/c (no. 14) with four formula units per unit cell and the following lattice parameters: a = 539.29 (4), b = 1556.41 (12), c = 1522.66 (11) pm, and β = 93.452 (4). The crystal structure comprises five crystallographically distinguishable Gd3+ cations, which are surrounded by either oxide and fluoride anions (Gd1–3) or by oxide anions only (Gd4, Gd5), with coordination numbers ranging between seven and nine. The fluoride anions are trigonal non-planar coordinated by three Gd3+ cations (Gd1–3). The distorted [WO6]6− octahedra in this structure form isolates edge- and vertex-connected entities of the compositions [W2O10]8− and [W2O11]10−, respectively. According to the presented units, a structured formula can be written as Gd4[FGd3]2[W2O10][W2O11]2. The single-crystal Raman spectrum reveals the typical symmetric stretching vibration mode of octahedral oxidotungstate(VI) units at about 871 cm−1

Tetrayttrium difluoride disilicate orthosilicate, Y4F2[Si2O7][SiO4]

In the crystal structure of Y4F2[Si2O7][SiO4], three fundamental building blocks are present, viz. anionic disilicate and orthosilicate units ([Si2O7]6− and [SiO4]4−) and cationic [F2Y4]10+ entities. The latter are built up by two [FY3]8+ triangles sharing a common edge. The four crystallographically independent Y3+ cations display coordination numbers of eight for one and of seven for the other three cations, provided by oxide and fluoride anions. The overall arrangement of the building blocks can be considered as layer-like parallel to the ac plane