(La3 Z x)Al and (Ce3 Z x)Al with Z = C, N, O: preparation, physical properties and chemical bonding of metal-rich perovskites

La26Ge19M5O5 (M = Ag, Cu): Rare-Earth Metal Suboxide Superconductors with [La18O5] Cluster Units

Herein we report two reduced rare-earth metal-based superconductors, La₂₆Ge₁₉M₅O₅ (M = Ag, Cu), that feature an unprecedented [La₁₈O₅] cluster composed of five oxygen-centered [La₆O] octahedra condensed through shared faces and capped with [Ge₄] butterfly rings. The structure, determined by single-crystal X-ray diffraction, crystallizes in a tetragonal space group (P4/nmm), with a = 15.508(2) Å and c = 11.238(2) Å. Resistivity and magnetic susceptibility measurements show onsets of superconductivity at T_c = 5.4 and 6.4 K for the Ag and Cu compounds, respectively. Applying high pressures, up to 1.3 GPa, results in increased superconducting transition temperatures (T_c = 6.8 K for Ag and 7.2 K for Cu compounds), with no sign of saturation.

Mechanically Stable Magnetic Metallic Materials for Biomedical Applications

The structural, electrical, and magneto-elastic properties of lanthanide base nitride (Ln = Dy-Lu) anti-perovskites were investigated using density functional theory (DFT). The reported structural outcomes are consistent with the experiment and decrease from Dy to Lu due to the decrease ofatomic radii of Ln atoms. According to the electronic band profile, the metallic characteristics of these compounds are due to the crossing over of Ln-f states at the Fermi level and are also supported by electrical resistivity. The resistivity of these compounds at room temperature demonstrates that they are good conductors. Their mechanical stability, anisotropic, load-bearing, and malleable nature are demonstrated by their elastic properties. Due to their metallic and load-bearing nature, in addition to their ductility, these materials are suitable as active biomaterials, especially when significant acting loads are anticipated, such as those experienced by such heavily loaded implants as hip and knee endo-prostheses, plates, screws, nails, dental implants, etc. In thesecases, appropriate bending fatigue strength is required in structural materials for skeletal reconstruction. Magnetic properties show that all compounds are G-type anti-ferromagnetic, with the Neel temperatures ranging from 24 to 48 K, except Lu₃Nin, which is non-magnetic. Due to their anti-ferromagnetic structure, magnetic probes cannot read data contained in anti-ferromagnetic moments, therefore, data will be unchanged by disrupted magnetic field. As a result, these compounds can be the best candidates for magnetic cloaking devices.

Aqua-bis-[2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole-κ(2)N(2),N(3)](trifluoro-methane-sulfonato-κO)copper(II) trifluoro-methane-sulfonate

2,5-Bis(pyridin-2-yl)-1,3,4-thia-diazole (denoted L) has been found to act as a bidentate ligand in the monomeric title complex, [Cu(CF(3)O(3)S)(C(12)H(8)N(4)S)(2)(H(2)O)](CF(3)O(3)S). The complex shows a distorted octahedrally coordinated copper(II) cation which is linked to two thia-diazole ligands, one water mol-ecule and one trifluoro-methane-sulfonate anion. The second trifluoro-methane-sulfonate anion does not coordinate the copper(II) cation. Each thia-diazole ligand uses one pyridyl and one thia-diazole N atom for the coordination of copper. The N atom of the second non-coordinating pyridyl substituent is found on the same side of the 1,3,4-thia-diazole ring as the S atom. The trifluoro-methane-sulfonate ions are involved in a three-dimensional network of O-H⋯O hydrogen bonds. C-H⋯N inter-actions also occur.

trans-Diaqua-bis-[2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole]cobalt(II) bis-(tetra-fluoridoborate)

The bidentate 1,3,4-thia-diazole ligand substituted by two 2-pyridyl rings (denoted L) has been found to produce the new monomeric title complex, [Co(C(12)H(8)N(4)S)(2)(H(2)O)(2)](BF(4))(2). The thia-diazole and pyridyl rings surrounding the Co atom are almost coplanar [dihedral angle = 4.35 (7)°]. The mean plane defined by these heterocyclic moieties makes a dihedral angle of 18.72 (6)° with the non-coordinated pyridyl ring. The Co(2+) cation, located at a crystallographic center of symmetry, is bonded to two ligands and two water mol-ecules in a trans configuration in an octa-hedral environment. The tetra-fluorido--borate ions can be regarded as free anions in the crystal lattice. Nevertheless, they are involved in an infinite two-dimensional network along the [010] and [101] directions of O-H⋯F hydrogen bonds.

Remarkable rare-earth metal silicide oxides with planar Si6 rings

New rare-earth silicide oxides, La10Si8O3 (1) and Ce10Si8O3 (2), were synthesized through high-temperature reactions of the pure elements under controlled oxygen atmosphere conditions. The remarkable silicides crystallize in a unique crystal structure (space group P6/mmm; a = 10.975(3) A (La) and 10.844(1) A (Ce); c = 4.680(1) A (La) and 4.561(1) A (Ce)) that features a 3-D framework of corner-shared O-centered (La/Ce)6 octahedra, reminiscent of hexagonal tungsten bronzes, with planar Si6 rings enclosed within its hexagonal channels. Band structure calculations indicate the compounds are metallic, with optimized La-Si bonds, and a benzene-like [Si6]6- anion. Compound 1 exhibits temperature independent paramagnetism. Compound 2 exhibits Curie-Weiss paramagnetism, and an antiferromagnetic ordering below 7 K.