Synthesis and crystal structure of layered molybdate NH4Co2OH(MoO4)2⋅H2O

A new compound NH 4 Co 2 OH(MoO 4 ) 2 ⋅H 2 O was prepared by precipitation of aqueous solutions of cobalt nitrate and ammonium heptamolybdate at pH = 7.5. The crystal structure was identified by X-ray powder diffraction (XRPD) and Rietveld refinement as a known polymorph of layered molybdates (Φ y ) with general formula AT 2 OH(MoO 4 ) 2 ⋅H 2 O ( A = NH 4 + , Na + , K + and T = Zn 2+ , Co 2+ , Cu 2+ , Ni 2+ ) and refined from a model based on that structure. The lattice parameters were refined with R- 3 space group (148) a = 6.1014(2) Å, b = 6.1014(2) Å, c = 21.826(1) Å, α = 90°, β = 90°, and γ = 120°.