Rare Earth Metal‐Rich Magnesium Compounds RE₄IrMg (RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy) and RE₂₃Ir₇Mg₄ (RE = La, Ce, Pr, Nd)

Abstract

Abstract The rare earth metal–rich compounds RE 4 IrMg ( RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy) and RE 23 Ir 7 Mg 4 ( RE = La, Ce, Pr, Nd) were synthesized from the elements in sealed tantalum tubes in an induction furnace. Several structures were investigated on the basis of X‐ray single crystal diffraction: P 6 3 mc , Z = 2, a = 1001.2(7), c = 2257.2(5) pm, wR2 = 0.0441, 2402 F 2 values, 74 variables for Pr 23 Ir 6.81 Mg 4 , Gd 4 RhIn type, $F{\bar 4}{\rm 3}m$ , Z = 16, a = 1438.3(2) pm, wR2 = 0.0490, 542 F 2 values, for La 4 IrMg, a = 1405.6(2) pm, wR2 = 0.0368, 451 F 2 values, for Nd 4 IrMg, a = 1381.2(2) pm, wR2 = 0.0541, 480 F 2 values, for Gd 4 IrMg, a = 1370.7(2) pm, wR2 = 0.0377, 392 F 2 values, for Tb 4 IrMg with 19 variables per refinement. All other compounds have been characterized by X‐ray powder diffraction data. Pr 23 Ir 6.81 Mg 4 crystallizes with a new structure type. The three crystallographically independent iridium atoms have trigonal prismatic praseodymium coordination with short Ir–Pr distances ranging from 285 to 300 pm. The trigonal prisms are condensed to a three‐dimensional network via common edges and corners. Voids in the network are filled by the coordination polyhedra of the Pr4 and Pr6 atoms and Mg 4 tetrahedra (312‐317 pm Mg–Mg). Similar structural motifs occur in the compounds RE 4 IrMg, however, with a different connectivity of the building groups. The crystal chemistry of both structure types is comparatively discussed.