Neutron diffraction study of Sr(BrO3)2· H2O: Statistical tests of intensity variances, refinement including weak and negative intensities

Abstract

Sr(BrO3)2 · H2O, Mr = 361.478, monoclinic, I2/c (conventional C2/c), a = 887.0(1), b = 761.1(1), c = 936.9(1) pm, β = 91.82(1)°, V = 0.6321 nm3, Z = 4, Dx = 3.80 g cm−3, λ (neutron) = 87.013 pm, μ = 0.0055 mm−1, F(000) = 215.0 fm, T = 297 K, R = 0.063, wR = 0.046, S2 = 1.48 (0.04), 1592 unique intensities, 58 parameters, refinement on |F|2 including weak and negative intensities. The intensities are checked for normal and independent distribution and for proper choice of their variances. A simple formula is applied to take weakening by extinction into account. The results are in agreement with X-ray data confirming the distinct anisotropy of the thermal ellipsoid of the water oxygen. The OH bond length is 93.9(1) pm, the HOH angle 112.9(1)°, the hydrogen bond length (H … O) 187.5(1) pm.