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

The magnesium‐rich intermetallic compound Nd_4.67Ru₃Mg_8.83 was synthesized from the elements in a sealed tantalum tube in a resistance furnace. Nd_4.67Ru₃Mg_8.83 was characterized by X‐ray powder and single crystal diffraction: new structure type,I4/mmm, tI66, a = 946.0(1), c = 1789.5(4) pm, wR2 = 0.0368, 725 F² values and 36 variables. Two of the five crystallographically independent magnesium sites show a small degree of Mg/Nd mixing. The ruthenium atoms have square anti‐prismatic Nd₄Mg₄ coordination. Always six of such anti‐prisms are condensed via common edges, leading to a CsCl analogous neodymium coordination for the Mg4 atoms. The two‐dimensional networks of edge‐sharing Ru@Nd₄Mg₄ antiprisms are condensed to a three‐dimensional network via Mg5@Mg3₄Mg1₄ cubes. The extended magnesium substructure shows a broad range of Mg–Mg distances from 308 to 351 pm.