Crystal structure of M(IO3)2metal iodates, twinned bypseudo-merohedry, with MII: MgII, MnII, CoII, NiIIand ZnII

Abstract

AbstractThe non-centrosymmetric materials Zn(IO3)2, Mn(IO3)2, Co(IO3)2, Mg(IO3)2and β-Ni(IO3)2have been synthesised by evaporation of nitric acid solutions of metal salts and lithium iodate. All these compounds are isostructural and their structures were characterised both by X-ray diffraction on powder and single crystals. They crystallise in the monoclinic crystal system, space-group typeP21(no. 4) with a pseudo-hexagonal lattice, as shown by the lattice parameters of Mn(IO3)2for example:a= 11.247(1) Å,b= 5.045(1) Å,c= 11.246(1) Å, β = 120.02(1)°,V= 552.5(1) Å3, Z = 4. This monoclinic symmetry witha∼cand β ∼ 120° leads to a three-individual pseudo-hexagonal twin by pseudo-merohedry. The structure reveals a three-dimensional network in which each octahedrally coordinated cation is linked to ten othersviaiodate bridges. All these metal iodates generate second harmonics.