Ytterbium metal reacts with PhEEPh (E = S, Se, Te) and elemental Se in pyridine to give (pyridine)(8)Yb(4)(SeSe)(2)(Se)(2)(mu(2)-SPh)(2)(SPh)(2), (py)(8)Yb(4)Se(SeSe)(3)(SeSeSePh)(Se(0.38)SePh), and (py)(8)Yb(4)Se(SeSe)(3)(SeSeTePh)(SeTePh), respectively. The SePh and TePh compounds contain a square array of Ln(III) ions all connected to a central Se(2)(-) ligand. Three edges of the square are ...