Tuning Connectivity in Hybrid Organic-Inorganic Antimony Halides through Reactant Concentration Effects

In this study, we report the synthesis and characterization of two hybrid organic in- organic (HOI) antimony halides using DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane) as the organic cation. Varying the concentration of the starting materials leads to dif- ferent oxidation states, resulting in different inorganic substructures ranging from iso- lated units to layers and a new interconnected metal halide framework. The structure of (DABCOH2)SbVCl7 (1) contains isolated [SbVCl6]– units separated by the organic cation. Mixed-valent (DABCOH2)12(SbIII)14(SbV)2Cl79(H3O)3(H2O)12 (2) features an interconnected framework of [SbIIICl6]3– units as well as [SbVCl6]– and an unprecedented octahedral chloride hydrate cluster. The material as well as the chloride hydrate cluster were characterized via single crystal X-ray diffraction and spectroscopic methods. Compound 2 was compared to the literature-known mixed-metal HOI (DABCOH2)4SbIII 2CuII 2Cl18(H2O)4, 1 which was obtained under the highest reactant concentrations. (DABCOH2)4SbIII 2CuII 2Cl18(H2O)4 also contains a chloride hydrate cluster, which was identified and characterized by solid state NMR in this work. Compound 2 is the first HOI antimony chloride with an interconnected framework structure, featuring a yet unknown network topology; it also contains the first structurally characterized chloride hydrate cluster, in which the chloride is located in the center of the wa- ter shell. These compounds show that by selecting appropriate organic cations and conditions, the chemical space of antimony halides can be systematically expanded by careful reaction control.