Zirconium dihydroxide chromate

The crystal structure of the title compound, Zr(OH)(2)CrO4, has been reinve stigated [Mark (1972). Acta Chem. Scand. 26, 3744-3756]. It is composed of ordered layers whose stacking in the c direction is disordered. The symmetr y of the superposition structure is tetragonal, space group I4(1)/amd with a = 6.8709 (1) and c = 29.0432 (2) Angstrom. The true OD structure has orde red layers of the dimensions a(L) = b(L) = 2a and c(0) = c/4, where co is t he spacing between adjacent layers. The Zr atoms are joined by double hydro xide bridges and the structure consists of infinite nets with the compositi on [Zr-3(OH)(6)-CrO4](n)(4n+), joined together in c direction by chromate g roups. The zirconium polyhedra are not influenced by the OD phenomenon.