Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The quaternary germanides <jats:italic>RE</jats:italic><jats:sub>3</jats:sub><jats:italic>T</jats:italic>Rh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub> (<jats:italic>RE</jats:italic> = Ce, Pr, Nd; <jats:italic>T</jats:italic> = Nb, Ta) were synthesized from the elements by arc‐melting and subsequent annealing in a muffle furnace. The structure of Ce<jats:sub>3</jats:sub>TaRh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub> was refined from single‐crystal X‐ray diffractometer data: new type, <jats:italic>Pbam</jats:italic>, <jats:italic>a</jats:italic> = 719.9(2), <jats:italic>b</jats:italic> = 1495.0(3), <jats:italic>c</jats:italic> = 431.61(8), <jats:italic>wR</jats:italic><jats:sub>2</jats:sub> = 0.0678, 1004 <jats:italic>F</jats:italic><jats:sup>2</jats:sup> values, and 40 variables. Isotypy of the remaining phases was evident from X‐ray powder patterns. Ce<jats:sub>3</jats:sub>TaRh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub> is a new superstructure variant of the aristotype AlB<jats:sub>2</jats:sub> with an ordering of cerium and tantalum on the aluminum site, whereas the honey‐comb network is built up by a 1:1 ordering of rhodium and germanium. This crystal‐chemical relationship is discussed based on a group‐subgroup scheme. The distinctly different size of tantalum and cerium leads to a pronounced puckering of the [Rh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub>] network, which shows the shortest interatomic distances (253–271 pm Rh–Ge) within the Ce<jats:sub>3</jats:sub>TaRh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub> structure. Another remarkable structural feature concerns the tantalum coordination with six shorter Ta–Rh bonds (265–266 pm) and six longer Ta–Ge bonds (294–295 pm). The [Rh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub>] network fully separates the tantalum and cerium atoms (Ce–Ce > 387 pm, Ta–Ta > 431 pm, and Ce–Ta > 359 pm). The electronic density of states DOS from DFT calculations show metallic behavior with large contributions of localized Ce 4f as well as itinerant ones from all constituents at the Fermi level but no significant magnetic polarization on Ce could be identified. The bonding characteristics described based on overlap populations illustrate further the crystal chemistry observations of the different coordination of Ce1 and Ce2 in Ce<jats:sub>3</jats:sub>TaRh<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub>. The Rh–Ge interactions within the network are highlighted as dominant. The bonding magnitudes follow the interatomic distances and identify differences of Ta bonding vs. Ce1/Ce2 bonding with the Rh and Ge substructures.</jats:p>