The Rare Earth Metal-Rich Indides RE ₄RhIn (RE = Gd–Tm, Lu)

Summary.

The rare earth-transition metal-indides RE ₄RhIn (RE = Gd–Tm, Lu) were prepared by arc-melting of the elements and subsequent annealing. Single crystals were grown via slowly cooling of the samples. The indides were investigated via X-ray powder diffraction and several structures were refined from X-ray single crystal diffractometer data: $F{\bar 4}3m$, a = 1370.7(9) pm, wR2 = 0.049, 428 F ² values for Gd₄RhIn, a = 1360.3(6) pm, wR2 = 0.028, 420 F ² values for Tb₄RhIn, a = 1354.5(2) pm, wR2 = 0.041, 380 F ² values for Dy₄RhIn, a = 1349.2(3) pm, wR2 = 0.029, 410 F ² values for Ho₄RhIn, a = 1342.5(5) pm, wR2 = 0.037, 403 F ² values for Er₄RhIn, a = 1337.8(3) pm, wR2 = 0.038, 394 F ² values for Tm₄RhIn with 14 variable parameters per refinement, and a = 1329.7(3) pm for Lu₄RhIn. In this new structure type, the rhodium atoms have a trigonal prismatic rare earth coordination. Condensation of the RhRE ₆ prisms leads to a three-dimensional network which leaves voids that are filled by regular In₄ tetrahedra (317 pm In–In distance) in Gd₄RhIn. The indium atoms have twelve nearest neighbors (3 In + 9 RE) in icosahedral coordination. The gadolinium atoms build up a three-dimensional, adamantane-like network of condensed, face-sharing empty octahedra.