The structure of amorphous CrS3 containing [Cr-2(III)((S-I)(2))(3)](x) chains: An X-ray diffraction modeling study

The amorphous chromium sulfide, CrS3, has no crystalline counterpart. A mod el is constructed to account for the interference function, Qi(Q), and the real space total correlation function, T(r), obtained from X-ray diffractio n measurements. The structural unit (S-I)(2/2)Cr-III((S-I)(2)))(2)Cr-III(S- I)(2/2) gives a good fit to the (Q-space data over the range 2-20 Angstrom( -1) and explains features in T(r) to 3.6 Angstrom. The unprecedented coordi nation geometry around chromium explains the unusual magnetic moment of the compound, corresponding to one unpaired electron per Cr-III. The individua l structural units are linked by the terminal disulfide groups to give [-Cr (S-2)(2)Cr(S-2)-](n) chains. The flexibility of the single disulfide linkag es within the chains and the difficulty of rearranging these chains to form an ordered structure after the rapid formation of CrS3 from solution expla ins the amorphous nature of CrS3. (C) 1999 Academic Press.