Lithium hydrogenselenite, LiHSeO3 : Structure refinement using multiple-wavelength synchrotron radiation data

The crystal structure of LiHSeO 3 has been redetermined using synchrotron radiation X-ray diffraction data collected up to sin θ/λ = 0.575 A -1 at five different wavelengths, four close to the Se K-absorption edge (0.97974 A), the fifth at 0.560 A. Each data set was initially refined separately (460-470 unique reflections, 53 parameters), but a joint refinement of all data (2319 reflections, 61 parameters) resulted in substantially decreased standard deviations of atomic parameters and derived quantities. LiHSeO 3 crystallizes in the orthorhombic and non-centrosymmetric space group P2 1 2 1 2 1 [Z = 4, a = 5.0551 (2) A, b = 11.1874(6) A, c = 5.2202(3) A, V = 295.22(8) A 3 ]. Its crystal structure consists of pyramidal HSeO 3 - ions with two shorter Se-O [both 1.660(1) A] and one longer Se-OH [1.782(1)A]. The HSeO 3 - are linked into spiral chains along [100] by hydrogen bonds [O(3)... O(1) = 2.622(1) A, O(3)-H = 0.77(2) A, O(1)... H = 1.87(2) A]. Each of the Li + is tetrahedrally surrounded by oxygens at distances 1.910(2) A, 1.943(2) A, 1.968(3) A, and 2.021(3) A, joining the HSeO 3 - chains into a space-filling three-dimensional network.