Syntheses, structures, and magnetic properties of the europium(II) selenido pnictogenates(III), EuPnSe3 (Pn=Sb, Bi)

EuPnSe3 (Pn=Sb, Bi) have been synthesized through the reaction of Eu with Pn2Se3 (Pn=Sb, Bi) and Se at 850–900 °C. These compounds are isotypic with SrPnSe3 (Pn=Sb, Bi) and consist of square pyramidal PnSe5 units and distorted PnSe6 octahedra that form hollow columns that extend along the c-axis. These columns are separated by Eu2+ cations that occur as nine-coordinate tricapped trigonal prisms. There are also additional V-shaped triselenide Se32− anions between the columns that bind the Eu2+ cations. The Se⋯Se contacts (in EuSbSe3) in these units are 2.4584(11) and 2.4359(11) Å, which are consistent with Se–Se single bonds. The overall structure is chiral. Bond-valence sum calculations indicate that these compounds contain Eu2+. Magnetic susceptibility measurements provide values of 7.66 μB/Eu for EuSbSe3 and 7.64 μB/Eu for EuBiSe3, which are close to the expected free-ion moment for Eu2+. These compounds follow essentially Curie behavior from 300 to 5 K, and undergo an apparently antiferromagnetic transition below 5 K. Crystallographic data: EuSbSe3, orthorhombic, space group P212121, a=32.936(2)Å, b=15.406(1)Å, c=4.2622(3)Å, V=2162.7(2)Å3, Z=16Z=16, R(F)=2.63%R(F)=2.63% for 183 parameters and 5095 reflections with I>2σ(I)I>2σ(I); EuBiSe3, orthorhombic, space group P212121, a=33.307(2)Å, b=15.5804(9)Å, c=4.2274(2)Å, V=2193.7(2)Å3, Z=16Z=16, R(F)=2.68%R(F)=2.68% for 183 parameters and 4895 reflections with I>2σ(I)I>2σ(I).

Graphical AbstractThe isotypic compounds, EuPnSe3 (Pn=Sb, Bi), have been prepared as pure phases via the reaction of Eu with Pn2Se3 (Pn=Sb, Bi) and Se. Their structures consist of square pyramidal PnSe5 units and distorted PnSe6 octahedra that form hollow columns that are separated by Eu2+ cations and Se32− anions.Figure optionsDownload as PowerPoint slide