The crystal structure of the known compounds Ln 5 Re 2 O 12 (Ln = Y, Gd, Dy±Lu) and the new isotypic terbium rhenate Tb 5 Re 2 O 12 was determined from X-ray data of a twinned crystal of Ho 5 Re 2 O 12 : B2/m, a = 1236.5(4) pm, b = 748.2(2) pm, c = 563.8(1) pm, c = 107.73(3)°, Z = 2, R = 0.034 for 379 structure factors and 37 variable parameters. The rhenium atoms (oxidation number +4.5) have octahedral oxygen coordination. These ReO 6 octahedra share edges, thus forming infinite strings with alternating short and long Re±Re distances: 243.6(2) and 320.1(2) pm. Of the three holmium positions two are surrounded by seven oxygen atoms and the third one has octahedral oxygen coordination. The crystal structure of Pr 3 ReO 8 was refined from single-crystal X-ray data: P2 1 /a, a = 1498.0(2) pm, b = 749.09(8) pm, c = 610.48(9) pm, c = 110.39(1)°, R = 0.017 for 2082 F values and 110 variable parameters. It is isotypic with a structure first determined for Sm 3 ReO 8 . The new com-pounds Pr 3 Re 2 O 10 and Pr 4 Re 2 O 11 were prepared by reaction of elemental praseodymium with the metaperrhenate Pr(ReO 4 ) 3 . They were characterized through their X-ray powder diagrams. Pr 3 Re 2 O 10 was found to be monoclinic: a = 778.47(9) pm, b = 773.62(9) pm, c = 706.10(8) pm, b = 114.77(1)°.
It is isotypic with La 3 Os 2 O 10 and La 3 Re 2 O 10 . Pr 4 Re 2 O 11 crystallizes with Nd 4 Re 2 O 11 type structure with the tetragonal lattice constants a = 1272.49(3) pm, c = 562.29(2) pm. The compounds Nd 4 Re 2 O 11 and Sm 4 Re 2 O 11 are confirmed. The magnetic properties of Ho 5 Re 2 O 12 , Tb 5 Re 2 O 12 , Pr 3 Re 2 O 10 , Pr 4 Re 2 O 11 , Nd 4 Re 2 O 11 , and Sm 4 Re 2 O 11 were investigated with a Faraday balance. None of these compounds shows magnetic order above 200 K.