Solvothermal Synthesis, Crystal Structures, and Properties of New Selenidoantimonates [Ln(en) 4 (SbSe 4 )] (Ln = La, Nd) and [Sm(en) 4 ]SbSe 4 ·0.5en: The First Example of an SbSe 4 3– Anion Acting as a Ligand to a Lanthanide Complex

Three new lanthanide selenidoantimonates [Ln(en) 4 (SbSe 4 )] [Ln = La ( 1 ), Nd ( 2 )] and [Sm(en) 4 ]SbSe 4 · 0.5en ( 3 ) (en = ethylenediamine) were first synthesized by treating LnCl 3 , Sb, and Se in a stoichiometric ratio with en under mild solvothermal conditions. Compounds 1 and 2 are isostructural. The Ln 3+ ion has a nine‐coordinate environment involving eight N atoms from four en ligands and one Se atom from the SbSe 4 3– anion forming a distorted bicapped pentagonal bipyramid. [La(en) 4 (SbSe 4 )] and [Nd(en) 4 (SbSe 4 )] are the first examples of solvothermally synthesized selenidoantimonates with an SbSe 4 3– anion acting as a ligand in a lanthanide complex. The crystal structure of 3 contains an isolated bicapped trigonal‐prismatic coordinated [Sm(en) 4 ] 3+ cation, a tetrahedral SbSe 4 3– anion, and half a free en molecule in its asymmetric unit. The bandgaps of 2.22 eV for 1 , 2.33 eV for 2 , and 2.54 eV for 3 have been derived from optical absorption spectra. Compound 1 loses the en ligands in one step, whereas compound 2 loses them in two steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)