Reactions of Ln(SePh)(3) with SeO2 in THF give octanuclear oxoselenido clusters with the general formula (THF)(8)Ln(8)O(2)Se(2)(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 mu(3)-O2- ligands and mu(5)-Se2- ligands, with 14 bridging and two terminal selenolate ligands capping the cluster surface. Thermal decomposition at 700 degrees 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)(8)Nd8O2Se2(SePh)(16) and the fluorinated thiolate compound (DME)(2)Nd(SC6F5)(3) demonstrate that clusters with oxo ligands are not only highly emissive, but also they emit at wavelengths not found in conventional oxides.