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 inorganic (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 different oxidation states, resulting in different inorganic substructures ranging from isolated 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 octahedral chloride hydrate cluster. Compound 2, including its chloride hydrate cluster, was characterized by single-crystal X-ray diffraction, spectroscopic methods, and computational methods. Compound 2 was compared to the literature-known mixed-metal HOI (DABCOH2)4SbIII2CuII2Cl18(H2O)4, which was obtained under the highest reactant concentrations. This compound 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 water shell. These compounds show that by selecting appropriate organic cations and conditions, thechemical space of antimony halides can be systematically expanded by careful reaction control.