New Rhenium Chalcogenides with (Re6X8)-Cluster Units
Abstract A number of new ternary rhenium chalcogenides A2Re6X12 with A=Tl, Cu, Na, Cs; X=Se; A=Tl, Rb, X=S; and A2Re6X12 with A=Pb, X=S, Se, have been prepared using high temperature solid state reaction or ion exchange methods. These new phases are isostructural with K4Re6S12 (space group C2/c). The observed semiconducting and diamagnetic properties of these phases are consitent with the valence electron count (VEC) of 24. Tl and Re in Tl4Re6X12 (rmX=S, Se) have been confirmed by XANES to be in the +1 and +3 oxidation state, respectively. Ru can partially substitute for Re in Tl4Re6Se12 forming solid solutions of Tl4Re6−xRuxSe12. For x⩾0.5, Tl4Re6−xRuxSe12 shows metallic and antife romagnetic behavior which suggest the possibility of VEC greater than 24.