Solid Solutions RE16Rh11-xZx (RE = La, Ce, Pr, Nd, Sm; Z = Ga, Zn, Cd, In, Sn, Sb, Pb, Bi) - Centrosymmetric n=2 Variants of Parthe's Homologous Series A5n+6B3n+5

Several samples of solid solutions RE(16)Rh(11-x)Z(x) (RE = La, Ce, Pr, Nd, Sm; Z = Ga, Zn, Cd, In, Sn, Sb, Pb, Bi) were synthesized by high-frequency melting of the elements in sealed tantalum ampoules. The samples were characterized by powder X-ray diffraction, and the structures of eight compounds were refined on the basis of single-crystal X-ray diffractometer data. The compounds crystallize with a centrosymmetric variant (space group P4/mbm) of the Ca16Sb11 type (P42(1)m). The relation between both structure types is discussed on the basis of a group-subgroup scheme. Only for La16Rh8Sn3 we observed full rhodium-tin ordering. The striking structural motif is a chain of face-sharing square prisms (filled with tin) and anti-prisms (filled with rhodium). The La16Rh8Sn3 structure is closely related to the structure types W5Si3, Ca16Sb11, Y3Rh2, Sm26Co11Ga6, Pu31Pt20, and Yb36Sn23 and is the centrosymmetric n = 2 member of Parthe's A(5n+6)B(3n+5) series. Sn-119 Mossbauer spectra resolved the two crystallographically independent tin sites of La16Rh8Sn3, while a Pr16Rh9Sb2 sample shows only a singlet in its Sb-121 Mossbauer spectrum.