A Synthetic Route toward Layered Materials: Introducing Stereochemically Active Lone-Pairs into Transition Metal Oxohalides

The synthesis and crystal structure of eight new layered compounds in the (Mn2+, Fe2+)-(Sb3+, Te4+)-O-(Cl, Br) system are presented. Mn5Te4O12Cl2 (1), MnSb4O6Cl2 (2), Mn2Sb3O6Cl (3), Mn9Sb8O16Cl10 (4), Fe3Sb2O4Br4 (5), Fe7Sb10O18X8 [X = Cl (6), Br (7)], and Mn7Sb10O18Br8 (8). All of the compounds are made up of charge neutral layers held together through van der Waals interactions, except for compound 2, which has positively charged layers with halide ions between them that act as counterions. The transition metal atoms are confined in sheets within the layers and are thus well separated from each other along the stacking direction. The synthesis concept is based on utilizing both halide ions and p-elements having a stereochemically active lone pair that both act to open up crystal structures. This combination has proven to be a successful synthetic approach for finding new layered inorganic materials containing transition metals.