Abstract

The new chalcogenide CsCuFe2 has been prepared by solid state reaction of stoichiometric amounts of CuFeS2 and Cs2CO3 at 1280 K. This phase crystallizes in the ThCr2Si2-type structure with space group I4/mmm (No. 139), Z = 2, and cell constants a = 394.2(1) pm, and c = 1423.8(9) pm. The discrepancy indices of the single-crystal structure refinement were R = 0.054 and R(w) = 0.050. The sulfur atoms form layers of edge-sharing square pyramids pointing up and down with their apices. The Cu and Fe atoms are located in the remaining tetrahedral holes, while the Cs atoms are found in the interlayer region coordinated to eight sulfur atoms, forming a cube elongated along the c axis. The electronic structure is analyzed by means of extended Huckel tight-binding calculations. Our results show that this compound should be a metal and that the interactions between the transition metals atoms are largest for Fe-Fe pairs. (C) 1996 Academic Press, Inc.