Eu 3 Be 22 N 16 O: A Highly Condensed Oxonitridoberyllate

The oxonitridoberyllate Eu 3 Be 22 N 16 O was synthesized from Eu(NH 2 ) 2 , Be 3 N 2 and BeO in a W crucible under N 2 atmosphere in a radio‐frequency furnace at 1400 °C. The crystal structure was solved and refined from X‐ray diffraction data ( C 2/ c (no. 15), a =20.620(2), b =8.722(6), c =17.506(2) Å, β =120.782(3)°) and confirmed with Rietveld refinement methods as well as lattice‐energy calculations (Madelung part of lattice energy, MAPLE). Eu 3 Be 22 N 16 O consists of a rigid network of edge‐sharing Be X 4 ( X =N, O) tetrahedra and trigonal‐planar BeN 3 units resulting in a high degree of condensation κ =1.29. The charge of the anionic network is compensated by Eu 2+ . Magnetic susceptibility measurements exhibit Curie‐Weiss behavior above 2 K with an effective magnetic moment of 7.82  μ B /f.u., which is in accordance with the theoretical value for Eu II .