The crystal structures of 11 mixed-valency and mixed-metal salts A2M III 0.5Sbv 0.5X6 (A = Rb, Cs; M = Sb, Bi, In, Tl, Fe, Rh; X = Cl, Br) have been determined by powder neutron diffraction at 4.7 K and in several cases also at 298 and 423 K. Structures were refined by the Rietveld method. In five cases (A = Cs; M = Sb, Bi, Tl; X = Cl and A = Rb, Cs; M = Sb; X = Br), superlattice ordering of SbX6 - and MX6 3- was found (space group I41/amd) while the remainder were disordered (space group Fm3m). The presence of order or disorder correlates with the average MIII, V-X bond length. In Rb2SbIII 0 5Sbv 05Br6, the SbBr6 n- groups are also tilted from the 4-fold axis at 4.7 K (space group I41/a). Cs2SbIII 0.5Sbv 0.5Cl6 retains distinguishable SbCl6 - and SbCl6 3- up to 423 K. Other physical properties (vibrational spectra) are discussed in the light of the structural results.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry