Intermediate-valent Cerium in CeRu₂Mg₅

Abstract

The magnesium-rich compound CeRu 2 Mg 5 was synthesized by high-frequency melting of the elements in a sealed tantalum ampoule. CeRu 2 Mg 5 crystallizes with a new tetragonal structure type: P4 2 /ncm, a = 961.1(1), c = 723.2(1) pm, wR2 = 0.0284, 481 F 2 values and 25 variables. The striking structural motifs in CeRu 2 Mg 5 are short Ce-Ru distances of 232 pm. Each cerium atom is connected to two ruthenium atoms within a three-dimensional [Ru 2 Mg 5 ] network. CeRu 2 Mg 5 has a pronounced magnesium substructure with short Mg-Mg distances in the range 302 -341 pm. The short Ce-Ru distances are a consequence of the almost tetravalent character of the cerium atoms. Temperature-dependent magnetic susceptibility data show intermediate-valent behavior of the cerium atoms (0.9(1) µ B per formula unit) and no magnetic ordering down to 3 K.

Intermetallics La9Ru4In5 and Ce9Ru4Ga5 with new types of structures. Synthesis, crystal structures, physical properties

“…Finally, in other systems four intermetallics with short CeeRu distances were found: CeRuSn (2.330, 2.464 Å) [14,15], Ce 23 Ru 7 Cd 4 (2.582 Å) [16], Ce 23 Ru 7 Mg 4 (2.612, 2.754, 2.763 Å) [17], CeRu 2 Mg 5 (2.317 Å) [18] and Ce 2 RuZn 4 (2.601 Å) [19].…”

Nd4.67Ru3Mg8.83 – A Magnesium‐rich Compound with Ru@Mg4Nd4 Square Antiprisms and Mg@Mg8 Cubes as ­Basic Building Units

“…In the course of our systematic phase analytical studies of the RE – T –Mg ( RE = rare earth element; T = transition metal) systems,7 we also investigated the RE x Ru y Mg z compounds in more detail. Again, for Ce 4 RuMg,8,9 Ce 23 Ru 7 Mg 4 ,10 CeRu 2 Mg 5 ,11 and Ce 2 Ru 4 Mg 17 ,12 we observed shortCe ~IV –Ru distances. While these distances are moderately short for Ce 4 RuMg (282 pm) and Ce 23 Ru 7 Mg 4 (261 pm), they are drastically reduced in CeRu 2 Mg 5 (232 pm) and Ce 2 Ru 4 Mg 17 (231 pm).…”

The new cerium-rich intermetallic phase Ce13Ru2Sn5: Crystal structure and physical properties

“…Most striking shortest values of the Ce-Ru contacts (<2.40 Å) were firstly detected in numerous ternary indides: Ce 3 Ru 2 In 3 (2.38 Å [4]), Ce 16 Ru 8 In 37 (2.37 Å [5]), Ce 3 Ru 2 In 2 (2.23 Å [6], Ce 2 Ru 2 In 3 (2.32 and 2.37 Å [6]), and in the equiatomic stannide CeRuSn (2.33 and 2.46 Å [7,8]). Later Ce 5 Ru 3 Al 2 (2.53 Å [9]) and Ce 11 Ru 2 Al 6 aluminides (2.44 Å [10]) and two Mg-containing CeRu 2 Mg 5 (2.32 Å [11]), Ce 2 Ru 4 Mg 17 (2.31 Å [12]) intermetallics also with the drastically shortened Ce-Ru distances were investigated and supplemented this series. The short reviews considering Ce-Ru-based intermetallics with the shortened Ce-Ru distances may be found in [13,14].…”