Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand

Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en)2(dien)(η2-SbSe4)] (Ln=Ce(1a), Nd(1b)), [Ln(en)2(dien)(SbSe4)] (Ln=Sm(2a), Gd(2b), Dy(2c)), [Ln(en)(trien)(μ-η1,η2-SbSe4)]∞ (Ln=Ce(3a), Nd(3b)) and [Sm(en)(trien)(η2-SbSe4)] (4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe4]3− acts as a monodentate ligand mono-SbSe4, a bidentate chelating ligand η2-SbSe4 or a tridentate bridging ligand μ-η1,η2-SbSe4 to the lanthanide(III) center depending on the Ln3+ ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with Eg between 2.08 and 2.51 eV.