Preparation and Crystal Structure of the Carbides Ln12Re5C15 (Ln = Y, La-N d, Gd-Er)

Abstract

The title compounds were prepared by arc-melting of the elemental components and sub­sequent annealing. Their crystal structure is hexagonal P 6̅ 2 m with one formula unit per cell. It was determined from single-crystal X-ray data of La12Re5C15 (a =1116.8(1) pm, c =545.3(1) pm, R = 0.060 for 287 structure factors and 27 variable parameters) and Ho12Re5C15 (ia = 1066.7(1) pm, c = 504.2(1) pm, R = 0.018 for 392 F's and 31 variables). The structures correspond to the formula Ln12[ReC3]2[Re3C3(C2)3],where the brackets indicate two differ­ent trigonal planar anionic rhenium-carbon groups. The coordination of the rhenium atoms in these polyanions seems to be compatible with the 18-electron rule.