Vibrational Spectra and Magnetic Properties of Eu 3 [BN 2 ] 2 and LiEu 4 [BN 2 ] 3

Eu 3 [BN 2 ] 2 and LiEu 4 [BN 2 ] 3 were synthesized from a stoichiometric mixture of EuN, BN, europium metal and Li 3 N, EuN and BN (ratio: 1:4:3) in sealed niobium ampoules at 1475 and 1275 K, respectively. Temperature dependent susceptibility measurements of Eu 3 [BN 2 ] 2 and LiEu 4 [BN 2 ] 3 show Curie‐Weiss behavior with experimental magnetic moments of 8.03(5) and 8.5(1) μ B /Eu atom, respectively, compatible with divalent europium. Both nitridoborates order ferromagnetically at T C = 32.0(5) K (Eu 3 [BN 2 ] 2 ) and 22.0(5) K (LiEu 4 [BN 2 ] 3 ). The saturation magnetizations of 5.73(5) μ B /Eu atom at 5 K and 7 T for Eu 3 [BN 2 ] 2 and 4.2 μ B /Eu atom at 5 K and 2 T for LiEu 4 (BN 2 ) 3 are smaller than the maximum value of 7 μ B . 151 Eu Mössbauer data of Eu 3 [BN 2 ] 2 at 4.2 K show an isomer shift of —11.4(1) mm/s and an experimental line width of 3.1(2) mm/s. Full magnetic hyperfine field splitting with 26.2(3) T at the europium nuclei is detected. Vibrational spectra of Eu 3 [BN 2 ] 2 are interpreted on the basis of discrete [BN 2 ] 3— units with symmetry D ∞h by taking into account the existence of two crystallographically independent [BN 2 ] 3— anions and their dynamic coupling in the unit cell (factor group splitting).