Manganese (II) Bromide, anhydrous

Manganese Bromide (MnBr₂) is a pink crystalline solid.  It is hygroscopic, thus must be protected from moisture.  It is highly soluble in water and polar solvents such as ethanol.  It can be used as a catalyst in place of palladium in the Stille reaction.  It is also used as a reagent in the preparation of advanced ceramic and glass materials, such as LEDs or phosphors for lighting.

Researchers from Sung Kyun Kwan University in Suwon, Korea investigated both Manganese dibromide and Copper Iodide (CuI) in the presence of various alkali metal halide salts to replace Palladium catalyst for the Stille reaction.  Both Copper and Manganese were shown to cross-couple in organostannanes with aryl or vinyl halides.  Sodium Chloride and Potassium Chloride were the best at promoting the catalytic activity of the Manganese Bromide.

Manganese Bromide can also be used to dope Lead Bromide perovskite materials, used in phosphor materials for lighting.  For example, researchers from the University of California, Santa Cruz used Manganese Bromide to dope Cesium Lead Bromide (CsPbBr₃).  A different research group, from the FAMU-FSU College of Engineering in Tallahassee, Florida, was working with organic Lead Bromide perovskites.  The small amount of Mn²⁺ ions could tailor the white light emission of the materials from “cold” to “warm” depending upon the Manganese ion concentration.

Manganese dibromide can be used in other light-emitting materials as well.  Researchers from Dongguk University in Seoul, Korea have investigated hybrid Manganese compounds.  The coordination geometry around the Manganese ion changes the color of the light emitted from the material.  In one paper, they reported combining Manganese Bromide with a large cationic organic ligand, allyltriphenylphosphonium bromide ([(H2CQCHCH2)(C6H5)3PBr]).  The reagents were ground intimately, and the product was crystalized out of solution.  The organic ligand separated the [MnBr₄]^2- centers, enhancing their photo-luminescence.  The material was found to emit green light and was successfully incorporated into a phosphorescent green-light-emitting diode.

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