The Structure of Amorphous CrS3 Containing [CrIII2((S-I)2)3]x Chains: An X-Ray Diffraction Modeling Study

The amorphous chromium sulfide, CrS3, has no crystalline counterpart. A model is constructed to account for the interference function, Qi(Q), and the real space total correlation function, T(r), obtained from X-ray diffraction measurements. The structural unit (S-I)2/2CrIII((S-I)2))2CrIII(S-I)2/2 gives a good fit to the Q-space data over the range 2–20 ?-1 and explains features in T(r) to 3.6 ?. The unprecedented coordination geometry around chromium explains the unusual magnetic moment of the compound, corresponding to one unpaired electron per CrIII. The individual structural units are linked by the terminal disulfide groups to give [–Cr(S2)2Cr(S2)–]n chains. The flexibility of the single disulfide linkages within the chains and the difficulty of rearranging these chains to form an ordered structure after the rapid formation of CrS3 from solution explains the amorphous nature of CrS3.