Equiatomic rare earth rhodium plumbides RERhPb (RE=Y, La–Nd, Sm, Gd–Lu) with ZrNiAl-type structure

Abstract

Abstract The equiatomic plumbides RERhPb (RE=Y, La–Nd, Sm, Gd–Lu) were synthesized by induction melting of the elements in sealed niobium ampoules. The samples were characterized by X-ray powder diffraction, confirming their ZrNiAl-type structure, space group P6̅2m. Four structures were refined from single-crystal X-ray diffractometer data: a=769.42(5), c=415.60(3) pm, wR=0.0415, 343 F 2 values, 15 variables for LaRhPb, a=767.91(6), c=369.37(4) pm, wR=0.0798, 284 F 2 values, 15 variables for ErRhPb, a=767.01(8), c=366.21(4) pm, wR=0.0380, 341 F 2 values, 15 variables for YbRhPb and a=766.9(1), c=363.42(6) pm, wR=0.0699, 290 F 2 values, 15 variables for LuRhPb. The RERhPb plumbides contain two crystallographically independent rhodium atoms, both in tricapped trigonal prismatic coordination: Rh1@Pb3 RE 6 and Rh2@RE 6Pb3. Short Rh–Pb distances (277 and 284 pm in ErRhPb) are indicative of covalent Rh–Pb bonding. The crystal chemical details of the RERhPb series are compared with the silver plumbides REAgPb which show different transition metal-lead coloring. Temperature dependent magnetic susceptibility data show Pauli paramagnetism for YRhPb, LaRhPb and LuRhPb. An antiferromagnetic ground state below the Néel temperatures of 13.5, 21.0 and 6.9 K was found for PrRhPb, TbRhPb and DyRhPb, respectively. HoRhPb exhibits Curie-Weiss behavior in the observed temperature range.