Syntheses, structures, and magnetic properties of the europium(II) selenido pnictogenates(III), EuPnSe(3) (Pn = Sb, Bi)

摘要

EuPnSe(3) (Pn = Sb, Bi) have been synthesized through the reaction of Eu with Pn(2)Se(3) (Pit = Sb Bi) and Se at 850-900 degrees C. These Compounds are isotypic with SrPnSe(3) (Pn = Sb, Bi) and consist of square pyramidal PnSe5 units and distorted PnSe(6) octahedra that form hollow columns that extend along the c-axis. These columns are separated by Eu+ Cations that occur as nine-coordinate tricapped trigonal prisms. There are also additional V-shaped triselenide Se-3(2-) anions between the columns that bind the E cations. The Se center dot center dot center dot Se contacts (in EuSbSe3) in these units are 2.4584(22) and 2.4359(2) angstrom, which are consistent with Se-Se single bonds. The overall structure is chiral. Bond-valence SLIM calculations indicate that these compounds contain Eu2+ Magnetic susceptibility measurements provide values of 7.66 mu(B)/Eu for EuSbSe3 and 7.64 mu(B)/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 P2(1)2(1)2(1), a = 32.936(2) angstrom b = 15.406(1) angstrom, c = 4.2622(3) angstrom, V = 2162.7(2) angstrom(3), Z = 16. R(F) = 2.63% for 183 parameters and 5095 reflections with I > 2 sigma(I); EuBiSe3, orthorhombic. space group P2(1)2(1)2(1), a = 33.307(2) angstrom b = 15.5804(9) angstrom, c = 4.2274(2) angstrom, V = 2193.7(2) angstrom(3), Z = 16. R(F) = 2.68% for 183 parameters and 4895 reflections with I > 2 sigma(I). (C) 2006 Elsevier Inc. All rights reserved.