Oxoselenido Clusters of the Lanthanides: Rational Introduction of Oxo Ligands and Near-IR Emission from Nd(III)

Reactions of Ln(SePh)3 with SeO2 in THF give octanuclear oxoselenido clusters with the general
formula (THF)8Ln8O2Se2(SePh)16 (Ln = Ce, Pr, Nd, Sm). In this isomorphous series, the eight Ln(III) ions
are connected in the center by a pair of μ3-O2- ligands and μ5-Se2- ligands, with 14 bridging and two
terminal selenolate ligands capping the cluster surface. Thermal decomposition at 700 °C of the Nd
compound in vacuo led to the formation of a phase mixture of NdSe2, Nd2Se3, and Nd2O3. Near-IR emission
experiments on the (THF)8Nd8O2Se2(SePh)16 and the fluorinated thiolate compound (DME)2Nd(SC6F5)3
demonstrate that clusters with oxo ligands are not only highly emissive, but also they emit at wavelengths
not found in conventional oxides.