Mo6+ Cation Enrichment of the Structure Chemistry of Iodates: Syntheses, Structures, and Calculations of Ba(MoO2)2(IO3)4O, Ba3[(MoO2)2(IO3)4O(OH)4]·2H2O, and Sr[(MoO2)6(IO4)2O4]·H2O.

The three metal iodates Ba(MoO2)2(IO3)4O (1), Ba3[(MoO2)2(IO3)4O(OH)4]·2H2O (2), and Sr[(MoO2)6(IO4)2O4]·H2O (3) have been successfully synthesized by introducing second-order Jahn-Teller distorted Mo6+ cations by a mild hydrothermal method. Single-crystal X-ray diffraction (XRD) was used to determine the structures of the three title compounds. In compound 1, the [Mo2O11]10- dimers connect with the [IO3]- units by sharing oxygen atoms to form two-dimensional (2D) layers that are separated by the Ba2+ cations. For comparison, the [Mo2O11]10- dimers and the [IO3]- units are isolated in compound 2, and they are connected by the [BaO11]20- polyhedra forming a 3D network. For compound 3, the [MoO6]6- polyhedra link with each other by corner and edge sharing to build 2D corrugated layers with tunnels containing isolated [IO4]3- units. The [SrO9]16- polyhedra link the 2D corrugated layers to form a 3D network. The infrared (IR) spectra, the ultraviolet-visible-near-infrared (UV-vis-NIR) diffuse reflectance spectra, and thermal stabilities of compounds 1 and 2 are presented. In addition, the theoretical calculations are also carried out to evaluate their band gaps and density of states.