Aluminum Germanides of the Divalent Lanthanoides Eu and Yb: Synthesis, Structural Chemistry and Chemical Bonding (In German)

Abstract

The title compound is synthesized by solid state reaction of a stoichiometric mixture of the elements (573 K for 48 h and 773 K for 72 h). The compound is characterized by single crystal XRD, IR diffuse reflectance spectroscopy, charge transport and magnetic measurements, and TB-LMTO-ASA electronic structure calculations. MnSb 2 Se 4 crystallizes isostructurally with FeSb 2 Se 4 in the monoclinic space group C2/m with Z = 4. The compound is a narrow-bandgap p-type semiconductor and exhibits a large Seebeck coefficient, high electrical resistivity, and low thermal conductivity at 300 K. MnSb 2 Se 4 is paramagnetic at 300 K and undergoes an order/disorder antiferromagnetic transition with a Neel temperature of about 20 K. -(DJIEUTEDJEU, H.; MAKONGO, J. P. A.; ROTARU, A.; PALASYUK, A.; TAKAS, N. J.; ZHOU, X.; RANMOHOTTI, K. G. S.; SPINU, L.; UHER, C.; POUDEU*, P. F. P.; Eur. J. Inorg. Chem. 2011, 26, 3969-3977 57 Fe Moessbauer spectroscopy, single crystal XRD for (III) and (V), and magnetization measurements to study the effects of the number of crystal water molecules on the magnetic behavior. (III) and (V) crystallize in the triclinic space group P1 with Z = 1. All three compounds behave as metamagnets exhibiting very rare field-induced antiferro-ferro-paramagnetic transitions. The number of crystal water molecules has a major effect on the Neel temperature, critical field, and magnetic hardness of the compounds in the ferromagnetic state. The materials behave as molecular magnetic sponges, changing their magnetic properties due to the reversible and controllable dehydration/hydration process. -(HERCHEL*, R.; TUCEK, J.; TRAVNICEK, Z.; PETRIDIS, D.; ZBORIL*, R.; Inorg. Chem. 50 (2011) (1 ≤ n ≤ 5). -The new series of title compounds is prepared by arc melting of stoichiometric mixtures of the elements and characterized by XRD and magnetic measurements. The Ti 2 FeRu 5-n Rh n B 2 (1 ≤ n ≤ 5) compounds crystallize isostructurally in the space group P4/mbm with Z = 2 (Ti 3 Co 5 B 2 -type structure). All the phases order ferromagnetically below Curie temperatures between 220 and 390 K. The series exhibits an evolution from soft to semi-hard magnetic materials with decreasing valence electron count (i.e. decreasing n). -(FOKWA*, B. P. T.; LUEKEN, H.; DRONSKOWSKI, R.; Eur. J. Inorg. Chem. 2011, 26, 3926-3930, http 17 O NMR spectroscopy and ultrahigh-resolution electrospray ionization mass spectrometry to gain insight into the elementary reaction steps involved in the overall water oxidation process. The results are compared with those for an inactive but structurally related Co system, K 6 [Co(H 2 O)SiW 11 O 39 ] (II). It is suggested that the water oxidation capability of (I) is based on its stability at pH > 7 and on the specific binding mode of the water ligand to the Co center in the protected pocket-like active site of (I). -(LIEB, D.; ZAHL, A.; WILSON, E. F.; STREB, C.; NYE, L. C.; MEYER, K.; IVANOVIC-BURMAZOVIC*, I.; Inorg. Chem. 50 (2011) 18, 9053-9058, http Chem. 2011, 26, 4069-4076, http 16 ] with unus...

Electrochemical Reduction of Carbon Dioxide to Formic Acid

“…In contrast to binary and ternary germanides, where Yb tends to be trivalent,32 the rare earth elements Eu and Yb are obviously divalent in binary stannides and ternary Al stannides. This fact is not only illustrated by the isotypism of the Ca, Sr, Yb, and Eu title phases, but also by the unit cell volumes of the four compounds, which perfectly fit the ionic radii of Ln 2+ and the volume increments of the monoxides Ln O: The Yb compound exhibits the smallest volume, the unit cell volume of the Ca compound is only slightly (3.5 %) increased.…”