Synthesis, Structure and Antiferromagnetic Large‐Distance Long‐Range Coupling of the Ruthenate(V) Sr3(Ag2/3Sr1/6)RuO6

Black, air‐stable crystals of the new ruthenate(V) Sr3(Ag2/3Sr1/6)RuO6 were grown in a silver ampoule using KO2 as oxidative flux. X‐ray diffraction on single‐crystals revealed a rhombohedral structure with the space group R[[EQUATION]]c. Sr3(Ag2/3Sr1/6)RuO6 crystallizes isostructural to Sr4PtO6 in the K4CdCl6 structure type. By sharing trigonal faces, alternating [RuO6] octahedra and [(Ag2/3Sr1/6□1/6)O6] trigonal prisms form segmented chains running parallel to the crystallographic c‐axis. Eightfold coordinated strontium cations are located between the rods. Despite the wide spatial separation of the magnetic cations (588 and 594 pm), Sr3(Ag2/3Sr1/6)RuO6 shows antiferromagnetic order below the relatively high Néel temperature of 79 K in magnetic fields up to at least 9 T, as measurements of the magnetic susceptibility and heat capacity show. Despite the pseudo one‐dimensional character of the structure, the characteristic of the susceptibility indicates a three‐dimensional coupling of magnetic ions.