Sin título
Idioma
en
Article de revue
Este ítem está publicado en
Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie. 2010, vol. 636, n° 7, p. 1236-1241
Wiley-VCH Verlag
Resumen en inglés
The rare earth borides <i>RE</i>Ru<sub>4</sub>B<sub>4</sub> (<i>RE</i> = Ce, Pr, Nd, Sm) were synthesized from the elements by arc-melting and their crystal structures were studied on the basis of X-ray powder and ...Leer más >
The rare earth borides <i>RE</i>Ru<sub>4</sub>B<sub>4</sub> (<i>RE</i> = Ce, Pr, Nd, Sm) were synthesized from the elements by arc-melting and their crystal structures were studied on the basis of X-ray powder and single-crystal diffraction: LuRu<sub>4</sub>B<sub>4</sub> type, <i>I</i>4<sub>1</sub>/<i>acd</i>, <i>a</i> = 747.47(8), <i>c</i> = 1506.4(3) pm, <i>wR</i><sub>2</sub> = 0.0579, 362 <i>F</i><sup>2</sup> values for CeRu<sub>4</sub>B<sub>4</sub>, <i>a</i> = 751.3(2), <i>c</i> = 1507.1(5) pm, <i>wR</i><sub>2</sub> = 0.0724, 471 <i>F</i><sup>2</sup> values for PrRu<sub>4</sub>B<sub>4</sub>, <i>a</i> = 751.0(2), <i>c</i> = 1506.9(6) pm, <i>wR</i><sub>2</sub> = 0.0598, 384 <i>F</i><sup>2</sup> values for NdRu<sub>4</sub>B<sub>4</sub>, and <i>a</i> = 749.1(1), <i>c</i> = 1506.0(3) pm, <i>wR</i><sub>2</sub> = 0.0759, 413 <i>F</i><sup>2</sup> values for SmRu<sub>4</sub>B<sub>4</sub>, with 18 variables per refinement. Striking structural motifs of the <i>RE</i>Ru<sub>4</sub>B<sub>4</sub> structures are Ru<sub>4</sub> tetrahedra and B<sub>2</sub> dumbbells with Ru-Ru and B-B distances of 271 and 180 pm in CeRu<sub>4</sub>B<sub>4</sub>. The intermediate valence of cerium leads to shorter Ce-Ru distances of 292 pm. CeRu<sub>4</sub>B<sub>4</sub> behaves like a Pauli paramagnet with a small room temperature susceptibility of 1.5 × 10<sup>-4</sup> emu<b>·</b>mol<sup>-1</sup>. Chemical bonding analyses shows substantial Ru-B and B-B bonding within the [Ru<sub>4</sub>B<sub>4</sub>] substructure.< Leer menos
Orígen
Importado de HalCentros de investigación