Dark red single crystals of PrLnYb 2 S 6 (Ln=Pr/Yb, Tb, Dy) have been synthesized through the reactions of elemental rare earth metals and S using a Sb 2 S 3 flux at 1000°C. These isotypic compounds adopt the F-Ln 2 S 3 three-dimensional open-channel structure type. Eight-coordinate Pr 3+ ions sit in the channels that are constructed from three different edge-shared double chains running down the b-axis that contain Yb(1)S 6 octahedra, Yb(2)S 6 octahedra, and LnS 7 monocapped trigonal prisms. Each double chain connects to four other neighbors by sharing vertices and edges. Considerable disordering in Ln positions was observed in single X-ray diffraction experiments only in the case of Pr/Yb. Least-squares refinements gave rise to the formulas of Pr 1.34 Yb 2.66 S 6 , of PrTbYb 2 S 6 , and PrDyYb 2 S 6 , which are confirmed by the elemental analysis and magnetic susceptibility measurements. Pr 1.34 Yb 2.66 S 6 , PrTbYb 2 S 6 , and PrDyYb 2 S 6 are paramagnetic down to 2K, without any indications of long-range magnetic ordering. The optical transitions for Pr 1.34 Yb 2.66 S 6 , PrTbYb 2 S 6 , and PrDyYb 2 S 6 are at approximately 1.6eV. Crystallographic data are listed as an example for PrTbYb 2 S 6 : monoclinic, space group P2 1 /m, a=10.9496(10)Å, b=3.9429(4)Å, c=11.2206(10)Å, β=108.525(2)°, V=459.33(7)Å 3 , Z=2.