Synthesis and crystal structure of the isotypic rare earth thioborates Ce[BS3], Pr[BS3], and Nd[BS3]

The orthothioborates Ce[BS3], Pr[BS3] and Nd[BS3] were prepared from mixtures of the rare earth (RE ) metals together with amorphous boron and sulfur summing up to the compositions CeB3S6, PrB5S9 and NdB3S6. The following preparation routes were used: solid state reactions with maximum temperatures of 1323 K and high-pressure high-temperature syntheses at 1173 K and 3 GPa. Pr[BS3] and Nd[BS3] were also obtained from rare earth chlorides RECl3RECl3 and sodium thioborate Na2B2S5 by metathesis type reactions at maximum temperatures of 1073 K. The crystal structure of the title compounds was determined from X-ray powder diffraction data. The thioborates are isotypic and crystallize in the orthorhombic spacegroup Pna21 (No. 33; Z=4Z=4; Ce: View the MathML sourcea=7.60738(6)Å, View the MathML sourceb=6.01720(4)Å, View the MathML sourcec=8.93016(6)Å; Pr: View the MathML sourcea=7.56223(4)Å, View the MathML sourceb=6.00876(2)Å, View the MathML sourcec=8.89747(4)Å; Nd: View the MathML sourcea=7.49180(3)Å, View the MathML sourceb=6.00823(2)Å, View the MathML sourcec=8.86197(3)Å) . The crystal structures contain isolated [BS3]3‐[BS3]3‐ groups with boron in trigonal-planar coordination. The sulfur atoms form the vertices of undulated kagome nets, which are stacked along [100] according to the sequence ABAB. Within these nets every second triangle is occupied by boron and the large hexagons are centered by rare earth ions, which are surrounded by overall nine sulfur species.