Synthesis and Characterization of Eight Compounds of the MU(8)Q(17) Family: ScU8S17, CoU8S17, NiU8S17, TiU8Se17, VU8Se17, CrU8Se17, CoU8Se17, and NiU8Se17

International audience ; The solid-state MU(8)Q(17) compounds ScU8S17, CoU8S17, NiU8S17, TiU8Se17, VU8Se17, CrU8Se17, CoU8Se17, and NiU8Se17 were synthesized from the reactions of the elements at 1173 or 1123 K. These isostructural compounds crystallize in space group C-2h(3), - C2/m of the monoclinic system in the CrU8S17 structure type. X-ray absorption near-edge structure spectroscopic studies of ScU8S17 indicate that it contains Sc3+, and hence charge balance is achieved with a composition that indudes U3+ as well as U4+. The other compounds charge balance with M2+ and U. Magnetic susceptibility measurements on ScU8S17 indicate antiferromagnetic couplings and a highly reduced effective magnetic moment. Ab Initio calculations find the compound to be metallic. Surprisingly, the Sc-S distances are actually longer than all the other M-S interactions, even though the ionic radii of Sc3+, low-spin Cr2+, and Ni2+ are similar.