Synthesis and structure of tetrakis(tetramethylammonium) octacosachlorooctaantimonate(III) [(CH 3) 4N] 4Sb 8Cl 28

The reaction between antimony trichloride and tetramethylammonium chloride in nitromethane gives transparent, irregular crystals of tetrakis(tetramethylammonium) octacosachlorooctaantimonate(III) [(CH₃)₄N]₄Sb₈Cl₂₈. Crystals are triclinic, space group P-1, a=11.846(2), b=12.217(2), c=14.120(3) Å,α=95.71(3), β=101.39(3), γ=118.59(3)°, V=1713.7(5) ų,Z=1, d_c=2.193, d_m=2.17(2) Mg m^-3. The structure contains a structurally novel Sb₈Cl₂₈^4- anion. It is composed of eight deformed octahedra, connected with each other by faces. In cavities formed by inorganic sublattice are located two crystallographically nonequivalent tetramethylammonium cations. One of them is disordered in such a way that all (C, N, H) atoms are split between two positions with occupancy factors 0.5.