ORIENTATIONAL DISORDER OF THE NITRITE ANION IN THE SODALITE NA8(ALSIO4)6(NO2)2

M(r) = 990.30, cubic, P4BAR3n, a = 8.923 (1) angstrom, V = 710.45 angstrom 3, Z = 1, D(m) = 2.35, D(x) = 2.31 Mg m-3, lambda(Mo K-alphaBAR) = 0.71073 angstrom, mu = 0.70 mm-1, F(000) = 488, room temperature, R = 0.021 for 304 unique observed reflections. The sodalite framework is an ordered and alternating array of corner-sharing AlO4 and SiO4 tetrahedra. Each polyhedral [4(6)6(8)] cage contains four Na cations which surround tetrahedrally an NO2 anion. The N atom is placed about 0.37 angstrom away from the centre of the cage. The orientational disorder of the anion is at least twelve-fold, and strong interactions of its N and O atoms with Na cations exist.